Apple hasn't patented cash back, no fees, or ease of use. The other banks are free to copy most of these ideas if they're prepared to.
Look at the personal finance scene in the UK—it's one of the more vibrant markets for banking right now with the likes of Monzo, Revolut, Monese, and countless others. Convenience and simplicity has prior art there.
But none of them integrate as well as Apple Card. And none of the other brand are as trusted as Apple. Unless other big banks offer something similar, people will choose a well known brand that offer these capabilities and not some unknown ones.
Look at the personal finance scene in the UK—it's one of the more vibrant markets for banking right now with the likes of Monzo, Revolut, Monese, and countless others. Convenience and simplicity has prior art there.