This is one of the great truths of politics, one that political actors exploit for advantage or ignore at their peril.
Suppose that there is a moral norm against littering in your neighborhood. You support the norm even when it is not convenient for you to do so. When someone litters, you could be upset simply because littering is harmful (the pure utilitarian attitude), or you could be upset that they are getting an unfair advantage by breaking the (unwritten) rules. People hate the feeling that others are gaining an unfair advantage over them by failing to live up to relevant norms or exploiting legal loopholes, they will sometimes incur significant personal costs to prevent being taken advantage of.
Some recent political examples:
The war on welfare frequently involves claims about people cheating. Yes, these claims are often implicitly or explicitly specifically about black people cheating – race is a very important part of the story – but the cheating part is important too, it makes taxpayers feel they are being suckered, it creates resentment. The resentment is magnified because the (purported) cheaters are black, but the cheating/resentment is an important part of the story too.
The push for border adjustments in climate policy is being fueled by the desire in the U.S. and E.U. to prevent producers in other countries from gaining an unfair advantage over domestic producers subject to restrictions on fossil fuel use. There is a strong case for border adjustments (and, in fact, for tariffs on nations that do not strongly regulate fossil fuel use). But what sells on TV is resentment of an uneven playing field between foreign and domestic producers.
Finally, people who are vaccinated are increasingly coming to resent those who are unvaccinated, and this is leading to growing support for mandates and penalties of various sorts on the unvaccinated. The logic again is “I did my part and got the vaccine, but now we are experiencing another surge because you are not willing to do your part.” In this case, there is a “tipping point” effect layered on top of resentment – as more people get vaccinated, more people are primed to resent the unvaccinated. With a little luck, this will move vaccination rates up substantially; the real question is whether the resentment and pressure will wane when the current delta surge recedes.