It's really true, though. It's brutal, ugly work with no hope of an end.
Edit: Favorite paper on the topic: http://research.google.com/pubs/pub43146.html
Edit: Favorite paper on the topic: http://research.google.com/pubs/pub43146.html
Plumbers are entirely different. They have to get their hands dirty working on some awful systems, but they actually have to know what they're doing, get specialized training, etc. Soldering a proper joint with copper pipes isn't that easy, and if you screw it up, it'll leak later and cause a lot of property damage. Knowing which pipes and fittings to use where is specialized knowledge. It's not something you can just grab someone off the street and train them to do in 30 minutes. Of course, plumbers also cost a lot too, and the ones who are self-employed (rather than their assistants) generally do pretty well financially.