Electronics engineer here. I use my HP Prime G2 daily in the lab for basic things as well as quickly calculating complicated stuff, since you can pretty much program it to do whatever you want.

You might say why not use Python or Matlab?! It‘s true that you don‘t need a small handheld device to do engineering calculations where there is a ton of other much stronger and free options out there. But the thing is, a calculator is a pure dedication to one thing. You turn it on, you do your calculation, get the answer and move on. It gets out of your way. Plus it is a better feeling to type stuff using the dedicated buttons in a calculator than using a keyboard.

IIRC You don’t use them in the dumb kids class much, you use them a fair amount in the sort of smart class, and you don’t use them much in the actually smart class.

These have been standard equipment (that you buy, or the school loans out) in middle-class US high school math since the 90's (and gone basically unchanged since then). The math books even have content tailored to particular models so that you'll have to buy them instead of alternatives from other vendors.

Those are permitted in schools and even exams in the US, for example. That’s also why they’re often so limited, to make the exam cartels happy.

You may have gone to a poor high school and college. I saw plenty of calculator use in high school and college a long time ago.