Politician and business people realize that in order to keep the scam going, they need population growth. Locals arent making enough new people. So they conclude we need to bring more in. America’s been doing this for a couple of hundred years. Irish, Italian, Asian and now Central American/Mexican.
Trouble is, the USA didnt have nearly the social welfare programs and taxation back in the day compared to now. So when the business cycle dips, it cost lots-o-money.