You might want to have a look at the usage stats of payment cards (here specifically credit cards) globally. You would realise that usage is low in Europe, compared to the US. https://www.theglobaleconomy.com/rankings/people_with_credit.... Most payments are done with regular banking and/or bank specific cards. The latter are not accepted by online platforms, the former has indeed transfer fees in many countries. The grandparents explanations are valid.
I've lived in the EU my entire life, in three different countries. I have visited and have friends in many more countries. Literally everybody I know has either a visa or mastercard debit card. Yes, people dont use credit cards specifically, they use debit cards, but it literally does not matter, the infrastructure is the same. Seeing ignorant Americans talk about Europe online like it's some backwater that doesn't even have card payment, is frankly offensive.
>The latter are not accepted by online platforms
This is not true.
"Bank specific cards" are actually debit cards. As an EU-based end user I see basically no practical difference between the two (I have both a MasterCard credit card and a Visa debit card), except that many US-based online stores' payment processors refuse to work with a debit card.