It's similar to how prostitution seems more ethical than telemarketing - one involves voluntary exchange of value between two willing consenting parties, the other involves harassing people and, frequently, trying to scam them.
"Prostitute" has negative historical connotations. For example, we will say that Mitch McConnell has prostituted himself to billionaires, but we would never call him a sex worker.
/ducks
I don't think that's technically true.
But I would say at the very least "sex work" covers dominatrices, pre-recorded and live-streaming porn performances, strip club and lap dance performances, as well as escorts. So "sex worker" isn't precisely equal to "prostitute"
This is demonstrably untrue.
I agree with your second sentiment (although I wouldn't generalize to "scumbags"), but there are a lot of people out there doing jobs that are extremely unpleasant, for far less money than prostitution can make.
If you don't have to fear your customer because the legal system has your back (making you independent of pimps and the like), prostitution is a possible way to make a significant amount of money - on your own conditions, in your own time, without the fear of being fired and all the other stuff a normal workplace imposes.