Plumbers and carpenters are not the the jobs being displaced right now.
Everyone needs a job.
So what happens when 10% of the population lose their job and there are none left to fill?
We see what happens first hand: people with 10 years experience in management being told they are underqualified to work at a giftshop. Or even worse told they are "overqualified" and the job just goes to Susan's 18 year old college kid.

What do you think happens to the economy when every single truck driver in the country suddenly finds themselves out of a job due to self-driving cars and AI? Yeah, the plumbers will be just fine. Not the point. You've ironically used an oversimplification to accuse me of oversimplification. Such is the complexity of this issue.