With the understanding that the answer may very well be “because thats not how they do it”…
Anybody know why air mattresses/rubber rafts/inflatable pools aren’t made with schrader valves? Seems like they’ve all got a silly little valve like you find on a beach ball, or some larger proprietary valve made to work only with their brand of pump (which generally comes with the object, so I’m ruling out marketing gimmick).
So you can blow them up with your mouth? When I was a kid, all we had that fit Shrader valves were manual pumps, which were good where we needed low volume and high pressure, but would have really friggin’ sucked to try to blow up a raft with. Not that using your mouth was fun, but just better.
Low pressure items also typically use a higher volume of air, and the Shrader is such a small diameter that you can’t move air through it quickly enough.
There’s also the fact that those things you mentioned are usually foldable for storage, so having a rigid metal valve that could easily tear a hole in it would be a bad idea.
$$$$
The rubber coated canvas floats we used at the beach in the past, OK, 40 something years ago, had brass Schrader valves. We’d fill them at the service station on the way, or if there was no desire to tie it to the top of the car, with a hand pump.
Actually that kind of reminds me that my favorite beach toy when I was younger wasn’t any of the plastic stuff that had non-Schrader valves anyway, but true tire inner tubes, the big ones, from tractors and commercial trucks. Tough, higher pressure, resilient, and a general blast.
I don’t know where to get inner tubes today, other than for bicycles.
I guess I’d have started regularly going to the beach just around 30 years ago, and so the rubber-coated canvas must have died out shortly before then. I have no recollection of that type of material used for anything beach-related.
The quality of the plastic stuff today seems to pale in comparison with the plastics of even my youth. I don’t know how any of it lasts or doesn’t fall apart at the seams. Our stuff lasted for years of daily, summer use. Yeah, daily – I lived 1/4 mile off of Lake Huron.
I think if you’re used to designing things to last, and if the first inflation technology you think of is tire inflation technology, the Schraeder makes perfect sense. But I guess it’s too easy for at least one of these things not to be true.
You can generally get truck inner tubes at larger tire stores or truck service shops. Unless it’s changed recently, large trucks with “split rims” require tubes because the rims themselves are not airtight. I got one three years ago.
I’m located in Missouri where there are a lot of streams used for canoeing. I’ve seen them also advertising tubing, so inner tubes can’t be too hard to find.
Of course there’s always the internet! http://www.tubeproinc.com/river-tubes.php Looks like less than $70 will get you going. 
Schrader valves are also tough to deflate when it’s time to head home. No one really wants to sit there for half an hour pressing on that little stem while a raft deflates.
Another issue is probably volume. Rafts, inflatable kayaks and such need lots of air, but not particularly high pressure air. So you want big valves to allow a lot of air movement.
Good point about the volume. I seem to remember rolling around on the float trying to get the air out.
Ok, that was easy.
Any time I see tubers today (we’re frequent canoeists), they’re all fake tubes. You know – that cheap plastic toy stuff. Good to see you can still get real ones.
There’s a few places around here you can rent tubes, and they’re all the old black-rubber-with-a-stem-valve type. A couple of students have the yellow plastic kind, but they ordered them online. As for inflation, the usual method is to just pick them up at the store already inflated, carry them inflated in a pickup truck or other spacious vehicle, and bring them back still inflated.
(A bunch of us physics students had our annual Geeks in the Creek float down the headwaters of the Missouri just a few weeks ago, and we all used real tubes.)