Or Burger King croisssanwiches or whatever? What’s the particular business case?
A false sense of urgency and exclusivity by limiting it only to breakfast? Some sort of volume and accessibility of ingredients expediency thing?
Most likely because they have to use the equipment to cook burgers and lunch stuff. The amount of equipment they have is limited.
If you want breakfast stuff all day go to IHOP , Bojangles, etc. Their menu does not change.
I actually read a book on McDonalds and basically the theory with McDonalds and other fast food places is, “We would if we could, and if it makes $$$$, then we can”
I talked to some people who worked at McDonalds, and it’s very well suited for assembly line processing. From what they tell me, there isn’t enough demand for breakfast products to disrupt the flow of the assembly line.
I worked at McDonald’s in the early 80’s. There was only one grill and there wouldn’t have been enough room to make eggs and burgers both during the lunch and dinner rushes.
That’s one helluva business model to tinker with.
You know, having it for only the breakfast hours sort of limits the supply and keeps it in line with the demand. It keeps it ‘special’.
Also, at least at Jack in the Box when I worked there in the early 90s, eggs were cooked at a lower temperature than burgers, so a section of the grill had to be specifically set aside for eggs in the morning and couldn’t be used for burgers.
They have the ability to make breakfast at any time during the day. Just Sunday I was getting some lunch at about 2PM, and one of the employees was eating a mcmuffin, hash browns and OJ on their break while I was waiting for my Big Mac.
eta: mcmuffin and hash browns were fresh off the assembly line
Sure, they have the ability. Generally there’ll be two grills. If it’s somewhat slow you can turn the temp down on one grill for the eggs or if you’re lazy you can just cook the egg on the burger temp and hope it turns out ok. Hash browns you just throw in the oil like fries.
However having the ability is not at all the same as that being efficient. If they offered egg mcmuffins all day I imagine that the wait time for food would at least double during their lunch and diner rushes.
The whole fast food business model is based on making the food before it’s ordered. A McDonald’s location knows that in a typical lunch rush, they’ll sell X Big Macs, Y Quarter Pounders, and Z Big-n-Tastys, and they’ll be continually making them to keep up with that amount. They can do this because they know that even if they don’t sell that Big Mac they just made right that moment, someone else will be along in a few minutes and order a Big Mac, and they can sell it to that person. But to sell McMuffins all day long, they’d need to either make them on demand, which is a lot slower, or have one or two McMuffins sitting under the heat lamps all day long in case someone orders one, that they’ll probably have to throw out anyway. Except that a McMuffin that’s been sitting under heat lamps for too long probably gets really unappealing, so they’d probably have to throw out one or two every hour.
What would be the reason since the breakfast sandwiched usually cost less, and it would seem to follow that they would make less money per order if they offered that alongside the regular menu?
They do serve breakfast if you are this guy.
Except that McDonalds went to make it as it’s ordered oh, about a decade ago. 
But we hashed this out in a thread not too long ago, though I cannot find it on my first search effort and I’m not spending 5 minutes waiting for try #2. In essence, it was determined that McDonalds would have to change their basic setup to accomplish it, because of the need for a grill cooking at a different temperature. Which doesn’t mean they couldn’t if they didn’t want to (witness the fact that Wendy’s is doing it), just that they don’t see a need sufficient to tinker with their current version of assembly line cooking (which, while it doesn’t assemble until ordered, does all the cooking of the burgers in advance, and puts the patties in a warmer for holding until assembly).
Wendy’s has breakfast? That’s new.
When I worked at McDonald’s in the very early 90’s (good job for a kid, by the way, honestly), there was excess grill capacity at most of the local stores. These were all corp stores, by the way, and they’ve mostly been rebuilt on their existing sites and turned into franchise locations, and so the capacity may no longer be there.
However by the time I was leaving, McD’s was changing to “staging” systems, which were big steam cabinets that ostensibly kept the hot, cooked ingredients fresh for longer periods of time. I’d call this an accumulator (or buffer) in the manufacturing world, and it allows discontinuous production of the cooked ingredients. I can’t imagine that it’d be difficult to squeeze in McMuffin ingredients, even with a reduced-capacity set of grills. The end result isn’t as much “made to order” as it is “assembled to order.” (Oh, yeah, and non-toasted buns still suck at McDonald’s. Why am I the only one who noticed oh those many years ago?)
Jack in the Box, Whataburger, and Sonic all have 24 hour breakfast (or did, in Texas, 10 years ago). Assuming that they all have less gross throughput than McDonald’s, and yet still manage to produce breakfast profitably at any hour, then my instincts would lean towards McDonald’s simply not wanting to sell breakfast at any hour, for some other reason that affects profitability (e.g., perhaps their breakfast hour sales would decline if breakfast were available at all hours [as said above, it keeps it special]).
If you’re reaaaaaaaaaaaaaaaaaaly nice and it’s a slow day there is a chance you can get breakfast at any time if you’re willing to wait (also assuming the staff is accommodating), but otherwise what everyone else said.
Put your trust in God and He’ll reveal the answer to your question very soon. 
Cross Whataburger off your list, at least in North Florida. Breakfast is 11 pm - 11 am. I live right down the street from one and, at least once a month, we have to sit around waiting for 11 so we can go get taquitos.
The ones around here did for a year or so, and had some dang tasty stuff… and then did away with it. Must not have been selling enough. 
I was just thinking about this the other day…our local McDonalds sells $1 Filet-O-Fish on Fridays, which is crazy. Whenever I go there on Fridays, which is, uh, almost every Friday, they’ll have a stack of about 20 or so waiting to go. So when you go there and make a reasonable order of, say, five or six of them, they’ll have them. I had a point here…something about Filet-O-Fish…oh yeah. Having that stack there really messes them up because the place is physically designed to make-as-ordered. They can’t have X number of Big Macs, Y number of chicken sandwiches, etc. because there is literally nowhere to put them.
Which reminds me…is it Friday yet?
Not crazy if there’s a big Catholic population, especially during Lent.