I think you're being a bit too sweeping, but your point doesn't apply only to tradespeople at all. The good ones are constantly learning and keeping up with new technology as much as any of us are. The lazy ones don't, and I know plenty of developers who only learn something new when they have to, and expect it to be delivered on a plate in the form of an offsite "training" session.

Home renovation is also where a lot of bottom-feeders end up. It's very easy to do and doesn't require much skill to get into.