This is a good observation.
The software that I spent most of my time with was a communication tool. So whenever something broke down, people had problems calling or texting one another. This pissed them off, naturally.
OTOH now my bestsellers are about half-forgotten events from world history. Aside from a weird e-mail I received from an even weirder Stalin-apologist, people generally enjoy this kind of reading and do not feel angry about it.
If, on the other hand, I were an investigative journalist and dug out dirt on politicans and mafia, the tone of the e-mails from readers would definitely get rougher, to say the least.
FWIW there are different types of writing and different types of programming.
Writing copy for a bank will probably generate a lot of feedback about mistakes that need to be fixed.
Writing code to reduce annoying monotonous tasks for coworkers so it takes ten minutes instead of two hours will get you a lot thank yous from your coworkers, and will also brighten your day.
It's all about what your job is, and how close you are to the people you are affecting.