Even if we start building a lot more stuff, you still don't need those construction workers. You have a GC to manage the whole project, aided by an AI who's handling scheduling/operations/logistics. You have a detailed plan to build against.

So why do you need former construction workers to manage the robots? Why can't the GC and management AI run the whole thing?

Maybe there's some scenario where you still need something like one licensed person from each skilled trade to be responsible for the robots employing those trades. But there's no way you need everyone who worked on building sites managing robots, no matter how much construction you're doing.

For which poor unemployed people who just got laid off due to AI are the Robots building house for? More abstractly, for whom are we creating are these productivity miracles and surplus for. Does a rich person suddenly need a million iPhones for himself and himself alone?

Labor costs are not the limiting factor on production.