In the early days.. I too would have been frustrated at the French checkouts.. having been used to the swift and impersonal attitudes in UK.
Now, we enjoy the fact that folk can (and do) take their time...whether it be organising a cheque.. chatting about a sick relative.. or whatever.
Re Credit Cards...When I was much younger (and foolish).. I decided that all the family would have lovely Christmas presents, not simply whatever I could afford, but something each one would really like...... and I ran up a large sum on my M&S card. Took me 2 years to finally pay off.. and I vowed "never again" and I've stuck to it. Only cheques and debit cards.. no credit, no overdraft.
Here in France, I wouldn't say we had to fight to get our money.. to get our Debit Card limit raised. I think the Bank were acting responsibly in the first instance, with new customers. They acted swiftly when we contacted them to ask for the limit to be raised.
I recall my brother gleefully telling me once (years ago in UK)...... Wow, Barclaycard have automatically upped my limit...look how much I can spend now!.. Seems the more he spent, the more they upped his limit. To my mind, that is really irresponsible.. not good at all.