The PM usually has autonomy to hit their goal in the method they see fit. The CEO/investor, while greedy, doesn't usually dictate execution (unless they are Steve Jobs).

Programmers are the ones implementing these designs, so they at the very least share culpability.

There's a difference though between "unethical" and just "shitty experience". A shitty experience is not inherently unethical. As a UX designer, I never did anything I believed to be unethical, but I did design many things that I thought were a shitty experience. I voiced my concerns, suggested some alternatives, and was told do design it to work the shitty way. If they want to pay me to design a shitty experience, then OK, the money's the same either way.

I just made sure to save the emails/documentation/etc. in case anyone tried to blame it on me when it failed or users complained. If the order came down from high enough up the org, a UX manager or director might also go on the record opposing it to cover for those under them in the org.

I think of it like hiring someone to replace all the beautiful hardwood floors in your home with thick, orange shag carpet. It's a bad idea and it will probably hurt the resale value of your home, but there's nothing unethical about the contractor accepting the work and taking your money as long as everything's done properly and to code.

There are degrees of evil though, surely?

I am not sure you’re making a reasonable or realistic argument when you are saying that someone should risk or give up their job, personal security, and stability of their family rather than implement a button to turn off iPhone notifications.

I don’t disagree with the principle at all, but if it’s ever going to change the conversation has to start somewhere rational. “Destroy your life because your UI offends me” isn’t it.

I'd be out of work entirely if I quit every job when I saw something disgusting. There are levels though.