Car-dependent suburbia is insolvent and requires incredible subsidies to avoid bankruptcy. This is because they're built by subsidies in the first place. They are Communist, not Capitalist.
To draw more of these subsidies, so they can pay the maintenance costs on the wealth-negative suburbs, cities need growth. Native populations are in decline, so they need to import foreigners.
It's nothing to do with labour. It's about scamming higher levels of government out of more money so they can pay for the suburbs. Note that it is functionally illegal in America to build anything but shopless condos or car-addicted suburbs. Having mandatory Communist living quarter designs is just what freedom means.
(For more, Seeing Like a State. Governments like things simplified so their boneheaded bureaucrats don't get confused. The book refers to legibility. Hence exactly two kinds of houses, completely unmixed with other kinds of buildings. Cartel and monopoly interests like to exploit this stuff too.)
While immigrants vote correctly (as opposed to voting right) the Regime scams the elections twice over anyway, so this explains very little. Merely a happy coincidence.
P.S. I believe the other driver is envy. Modern governments try to maximize envy. Importing incompetent immigrants makes them envy the more-competent natives, because now they're close enough to see the difference.