Hm? The ISP gives one IP address to a router in a house, that router uses NAT to let all the computers inside that house use the Internet through the one single shared public IP address. That's NAT, isn't it?

Well, in a strict sense, it is "you" who chooses to run a nat'ing router there, you could just have one single computer per ISP connection. Or have it run a proxy for you, or nat.

I mean, I understand that this feels normal today, that 10-20-50 devices need internet and that the way to manage that is to nat the connections, but your ISP isn't doing nat, it is you.

The model of "every Internet subscriber gets one IP address" only works thanks to NAT.