I’m a “sheltered young urbanite” but when I bring up the need for testing under a wide variety of real-life scenarios, I frequently get “ain’t nobody got time for that” from the PM (or management says yes, but does not provide enough resources).

There’s no need to make this an attack on the developers, I’m pretty sure they’re running into software development economic factors that transcend individual personalities here.

You're assuming this was a "didn't know" failure mode, not a "didn't care" failure mode.

I'd wager it was a "didn't care". They knew about the limitations, figured the product would work often enough to make some money and labeled everyone pointing out the problem as haters or technophobes.

Someone probably even pitched a keypad password based redundancy and got drown out in valley buzzwords about MVPs and shipping fast until they gave up.