I almost never use cash or checks; it's all debit for me with a rare credit card swipe for major purchases.
Kids don't know how to count back change because they don't have to count back change. If the register didn't tell them the amount (AND if people returned to using cash) they'd be as good at counting it back manually as older generations were.
Kids today are learning different skills from what many of us had to learn to get by in the society of the times. Now, if you came out of school unable to use a computer it would be a serious obstacle to going into most job markets, and entirely prohibitive for pursuing higher education. Those non-change-counting kids have to have computer skills to run the registers now.
Cursive writing is pretty, but is it truly necessary when we can block print or type communication? Paper forms are dying out, but even these now usually have a note to PRINT your name.
I'm not saying we should junk everything we were taught in favor of new things, but we should look seriously at what skills are needed and which ones are now only "nice to haves."