It is really pissing me off that "tubeless ready" wheels and "tubeless ready" tires have made it infinitely harder to just fit a tire with a good old tube inside.
With the exception of hookless rims (which are not common yet, at least here), TL wheels will take a clincher tire and tube, and TL tires will take a tube. The potential incompatibility comes from TL tires and TL wheels, not at all related to tubes, and is because of lack of spec and manufacturing tolerances.
rims with thick rim tape designed to seal with tubeless tires have much less gutter, so it's a bit more difficult to squeeze the last bit of the tire onto the rim. they're compatible, just difficult to work with.
I want to be able to fix a flat outside, not call an Uber.
I’ll echo your frustration 100%. I found Schwalbe Ones are much looser fitting and have no problem mounting them on two sets of rims I have that will barely take a GP5K.