When I buy a physical book, am I entitled to scan for myself?
I don't mean to distribute, but to scan for myself to read digitally, am I allowed to do that legally and ethically when I buy a physical book or would that be totally unethical and illegal?
It is legal but in any case why do you care. If it were illegal it's not something that would be enforceable or something they'd be likely to "catch" you for, and it's definitely not unethical. Everyone should be free to do whatever they want with published literature.