It's not evil because there's no harm being inflicted. Adults who consent to have sex and doing it on camera are not engaging in evil. A person consenting to watch the video is not engaging in evil. There are tangential harms such as abuse and exploitation of the actors, but that's not inherent to porn (there is ethically produced porn) nor unique to it (actors in Hollywood are also exploited). The answer to those problems are breaking down existing power structures and zealously protecting worker rights, not banning Pornhub and AMC Theaters.
I would hazard a guess that the average worker in a large number of low-wage blue collar fields feels that their job is more degrading than the average porn SW.
Regardless of line of work the solution is robust worker's rights protections and social safety nets, so that workers can't be exploited or financially pressured into jobs they find degrading, not to forbid the line of work or portray it as taboo.