Guilt-tripping isn't morally neutral. It's manipulation, exploitation, getting people to do what you want without giving them what they want. Doing it is evil and makes you evil. In my late teens and early twenties I constantly guilt-tripped people close to me. It was my "thing". It hurt everyone a lot. Then one day I realized how sick it was, and stopped completely. Now I never do it to anyone for any reason, and pu…
Also, "manipulation" suggests unfair trickery. If you're guilt-tripped for speeding in a school zone, is that unfair trickery? There are rules that are meant to constrain people from infringing on other people's rights and security. How are we supposed to enforce them? Should every anti-social activity be enforced by a fine or prison time? That's considerably harsher than a moment of social discomfort when you realize someone is shaming you.
Finally, calling this "evil" is exhausting your evaluative vocabulary too quickly. Guilt-tripping someone for anti-social behavior can certainly be less harmful than guilt-tripping them for pro-social behavior, which is less harmful than the anti-social behavior itself, and so forth.