I reviewed a book called Strings Attached: untangling the ethics of incentives by Ruth Grant for the Times Higher Education. You can read it here. Part of the main argument of the book, which I think does make sense, is that incentives are not just innocuous, voluntary trades, but tools some people use to get other people to do what they want them to do. Like persuasion and coercion, an incentive can be used in morally suspect ways.
The book goes into a little detail about why it is that incentives can sometimes backfire. It helped me to understand why I’ve always been annoyed when offered a loyalty card along with my coffee, and why I’ve always been suspicious of governmental incentive schemes. An incentive is a way to push you into action without reasoning with you, and that can be, in its own very particular way, seriously insulting.