I think part of the reason the trades look attractive is because relatively few people do them. If we had labor-intensive manufacturing then we could add say 10

I think part of the reason the trades look attractive is because relatively few people do them. If we had labor-intensive manufacturing then we could add say 100,000 low-skill jobs, but you can't add 100,000 tradespeople as easily without crashing their wages since there's a relatively fixed quantity of trade work that needs to get done.