In the US you basically always get a debit card with a bank account but not everyone gets a credit card, either because they are wary of credit or can't get a decent one.
US consumers have credit cards on top of debit cards because they really, really want access to credit. Even overdrafting is really common and a desirable feature for a large chunk of the US population.
You seemingly know much more about the backend than me, so I am still a little confused by your comment, about Interac, for example. The US system allows for consumer-to-merchant debit payments no problem, whatever fees there are are totally invisible to consumers. (I think it's lower than the credit interchange fee?) I can also transfer my money from bank to bank without fees, although sometimes it takes a couple days. Where it really falls down is peer-to-peer instantaneous transfers. There are different things becoming popular but I don't think any of them are particularly good, and reversibility is really important in the US market and systems like Zelle don't seem to appreciate that.
You already have a bank account, and your bank already knows how to talk to literally any other bank, because by law they have to all talk the same protocols, so you can just use your bank card to pay for everything, anywhere. No need for cards from private companies like Visa or Mastercard that saw a failed banking system and went "Let us fill that niche, it'll be so convenient! For a large fee, of course".
And it really is a failed banking system: the fact that Interac in North America was able to go "hey we 'invented' EFT and got your bank to sign onto that, because they refuse to directly talk to other banks so you can't move money from one account to another. It'll only cost you a dollar each time!" is just insane.