Why?

Because all of these countries have the same monetary system: fiat.

When you have an exponentially growing pile of debt, you need exponentially more tax revenue to cover it, as well as continually growing asset prices to allow the banks to continue lending against the pile of artificial crap.

And what's the easiest way to deal with this?

Import slave labour.

The business lobby loves it because they get cheaper slaves, and the government loves it because they get more tax revenue to fund their spending, whilst also pushing up asset prices through higher aggregate demand.

The banks love it because asset prices keep rising, and that funds their mortgage lending business unit, which makes up an increasing amount of their loans.

Western governments are corrupt.

Their actions benefit everyone except the citizens who elected them.