EU banks can only dream of the ways US banks get to freely completely rip off their customers (and commit major banking and trading frauds that crash the world economy without anybody going to jail).

Money gets lost. Either really or because you've experienced shrinkage. Tellers are not perfectly accurate. Customers will try to scam you with fake money, if you notice, that's your loss. If you pass enough of it on, you will at least have to answer some questions. If coins are involved in your change you're going to have a bad time.

Retail in the 80s was not particularly fun. Running register tapes to look for missing money was an effective nightmare.

It's probably that credit cards have filled an effective void for so long we haven't developed cash handling and tracking technologies to the same level. We almost got there. Remember for a few years when almost all grocery stores had automated change dispensers?

We optimized for a particular solution and ignored the other.