Why do you need to choose (or tell the worker) “credit” or “debit” when paying for something by card? Are the two cards built differently?

Question

Why do you need to choose (or tell the worker) “credit” or “debit” when paying for something by card? Are the two cards built differently?

In: Other

Answer 1

Every bank I’ve ever used all local charge for debit. Do the big banks not?