Sure, except now rim and tire manufacturers go to the opposite ends of manufacturing tolerances on their respective parts because no one wants some niche road tubeless setup popping off at 7 bar. The result is tires like the GP5k (not even TL version) where I've struggled to get even the first side over, on rims that are tubeless ready and, no coincidence, have a history of being difficult to fit tires on.

I want to be able to fix a flat outside, not call an Uber.

Ah fully understand, I thought you meant there is somehow incompatibility between tubes and TL wheels/tires.

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.

normally when fitting a tire, you put the bead on one side in the "gutter" in the center of the rim where the diameter is narrower while you lever on the bead on the second side. leaving the first bead loose and un-seated while you pop on the second bead makes it pretty easy.

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.

There are tire/wheel TL combos that are just not compatible, no matter what you try. Centering the tire is key, soapy water helps, you may need to warm up the tire, a tire jack may be needed in some cases .. but none of those will work 100% of the time, which is ridiculous.