I’d just order a value meal cheeseburger (~$1) and ask to hold everything except the bun and cheese. If the cashier refuses, go all 5 Easy Pieces on her.
I remember working my first job at a movie theater concession stand. 16 years old, of average intelligence, meek, and I spent the first month practically pissing myself whenever someone ordered something unusual. Often the lobby was loud and the customer would yell if I asked them to repeat themselves. They’d yell if I got it wrong. The manager would yell if I rang it up wrong, because it would fuck up inventory.
I’m not sure it would account for five separate experiences, but perhaps a couple of times you’ve gotten some new idiot teen who’s freaking out on top of everything. I could see it being a problem.
Aside: Once, in my food service days, I had a customer come to the window and ask for an order of extra cheese. It was on the menu, after all. After I clarified what she wanted, I gave her what she asked for, and everyone was happy.
(it turned out that she had previously ordered fries, got to her table, and then decided she’d rather have cheese fries, instead)
The local BK delivers and we’ve made use of that service about once a month. I can’t stand raw onions so I initially tried getting them to hold the onion. Gave up on that when my fourth burger arrived with onions and no tomatoes.
Fortunately, as far as my SO is concerned, the more onions the better! Now she gets extra at no charge whenever I order something that has onions on it.
Duh.
But not grilled-cheese sandwiches. Why not go to a diner?
Then I certainly hope you had your hairnets on.
It’s kids. Kids love the Clown, they have toys, the play area, etc. Except the OP’s kid wants a type of grilled cheese.
Now if you go to In & Out, they will make anything that can be made with their limited ingredients.
So, now the Op understands why it’s difficult for them to get his “simple” order straight, and we understand why his kids wants that. No need for aggro.
We didn’t wear hairnets. Too dorky. We had these cool baseball caps.
You’ve obviously never gone out to lunch with a bunch of friends.
I think ill try ordering a Burger with “extra buns”, and see if the universe explodes. 
I’m sure some would- but plenty wouldn’t. Even some people who might have questioned why a cheese sandwich and a burger were the same price price on the menu wouldn’t have had a problem when the cheese sandwich wasn’t on the menu.
I was a vegan in the 60’s and would ask for a ‘BLT’ and tell them to leave the bacon out . They never got it right , they kept trying to put the bacon in my sandwich . It was very hard to find any meal the was vegan in the 60’s , I would think it would be easier today. But I guess not.
Oh, they got it right. It is was YOU who were wrong. Leaving out bacon. That’s not something that even makes sense.
My father grew up in a kosher household, and he said his favorite sandwich as a kid was an “LT”. He only learned in college that most people ate BLTs.
40 years ago Mad Magazine gave us the answer…
Customer: I always have a special order so that I’ll get a fresh hamburger, “No Cheese please”
…cut to pimply youth crouched behind the back counter, pulling melted cheese off a hamburger… “I hate these special orders”
I did have trouble, at a Canadian McD’s where I’m sure she was bilingue anyway but I was trying to use French. “Numero trois avec pas de viand” for my veggie friend – but she got it right anyway! Miles later I realized “sans viand”! :smack: Dummkopf.
There is no reason McDo’s can’t do this for you. They do special orders all the time. Maybe they have no key to deduct the price of the meat patty from the the cheeseburger but they can still accommodate it. Anecdote the first:
In my youth (my salad days, if you will) I worked at Subway. One night a bunch of drunks came in after the bar closed and one fellow would not tell me what kind of bread he wanted. I asked several times and he would start digressing about lettuce and banana peppers. The line up was out the door so I just started piling the cheese and other condiments on the pre assembled slices of meat. It was extremely sloppy but everyone in the place cheered except the fellow who’s sandwich was leaking all over. His friends took our side and made him pay for and eat the mess. My cousin was working the till and we got away with it, although it was interesting math at the end of the day to account for having an extra bread.
Anecdote the second
When my ex husband worked for McDo’s 12 years ago they regularly recieved orders for Big Mac’s without meat. So basically all the fixings, without meat. Not every shift, but certainly every weekend these orders came through.
Third:
My son at age 3 or so went for a while where he wanted “salad burgers” which was a plain hamburger dressed like a junior chicken, with the shredded lettuce and mayo. Somehow I managed to get this conveyed correctly, and received correctly all the time at McDo’s. Because I had a crazy work schedule at the time and sometimes had to pick him up from day care, get him fed, and across town to an evening caregiver all on my 1 hour “lunch break” we probably did this at least every other week for three months. So it wasn’t a “one off” lucky chance.
I don’t know how to convey it, maybe "plain cheeseburger, with no meat. " But it is do able.
And good luck.
Maybe it’s a regional thing. My Mom is a vegetarian and she simply orders “a grilled cheese with medium fry” and they get it right all the time at McD’s. It’s an inversed bun with cheese toasted on the grill.
Oh believe you me, I check. Also for shoe treads and lugies 
Actually today I don’t think a restaurant would try that but I have been at places where they attempted to scrape the cheese off, or some of the cheese had melted onto the fries or whatever was on the plate and they tried to serve it to me again. Now if it happens, I cut into the sandwich to eliminate that possibility.
I once ordered a plain hamburger for the dogs along with a couple ordinary McMeals for the humans when we were traveling. Distract them with a little treat so they don’t poke their noses into our lunch…
I thought a “plain” hamburger would be a patty on a bun with no onions (bad for dogs) or ketchup (too messy for dogs in the car) and comments upthread seem to indicate I was thinking correctly. Once it cools for a few minutes, the bun tends to stick to the patty, so it’s easy to break off chunks that stay together until snarfed down by happy hounds, but a couple miles down the road, we discovered a plain burger at that location meant a patty wrapped in paper. No bun, but they at least left off the onions. Dogs didn’t care. 