So there will be some selection bias. You won't get a completely random population.
That's fine. Like, if you can't afford to move, then don't move. I don't support giving randos in Serbia free trips to America.
why would any jobs get higher wages?
Lets say a place has 300 million people and 30000 Actuaries. The ratio of people to Actuaries is 10K:1.
Lets say the population quintiples: 1.5 billion people and 75000 Actuaries. The ratio of people to Actuaries is 20K:1. The demand for Actuaries relative to the supply has doubled, leading to higher wages for Actuaries.
It takes time for infrastructure to be built and for businesses to expand to take advantage of the new work force.
Tell that to the Pilgrims. They built their settlement in 1-2 months with hunger, no bulldozers, and no mexicans.
It will be easy to acclimate the new population that won't have hunger (construction sites have food), a bunch of bulldozers, and a bunch of hard working Mexicans. I swear, their tacos and marajuana gives those Pablos and Javiers energy. I'm joking.
Over the long term things will eventually recover, but that could take decades (depending on how many people you are talking about).
It will probably take a few months.
because if you have enough housing for 1 million people, then suddenly have 2 million people, now you have 1 million homeless people. Over the course of years, you would be able to build more housing, expand businesses to make jobs for them etc. But if you do it too fast, you create poverty and death.
Tell that to the pilgrims; you can't go too fast.
They had lots of workers working on 1 single project.
That 1 project housed more people than the number of workers making that one project. Therefore, you won't need 1 billion people making 1 billion projects; maybe 1 million (1000 people per building).
building regulations aren't just about making sure it doesn't fall down. They are about making sure it's safe.
Empire State building was safe.
They are about making sure it is energy efficient (you wouldn't want to have to build a million coal power plants because you built shoddy housing with bad insolation).
They did this with the Empire State building.
Skipping them might let you build faster (it also might not) but you are going to get lower quality buildings and have alot more problems down the road.
The Empire State building is very high quality and has no major problems.