It is about what I suspected. There is big money pushing this immigration into the US.
Similar for Europe I imagine.
Honestly, the biggest money to be made from illegal immigration is at the Federal level. Social Security was always a ponzi scheme, and at a 1:1 replacement rate it is going to collapse. It requires closer to a 2:1 ratio of births, an ever increasing population level, to sustain it.
Illegals are a wonderful stopgap for that problem. They steal SSN's and pay taxes, but will not be able to claim SS benefits later on. Some do write EXEMPT on their paperwork, but some don't.
Sadly, they're an exploited underclass that no one acknowledges, stuck between a neighbor that doesn't want them around, and a home country overrun with corruption and narco violence. The conservatives should be more welcoming of them due to an old world catholic mindset, they're more likely to vote conservatively. A conservative reversal on the border wall problem, striving hard to filter true refugees from smugglers, would do wonders to boost conservative voter numbers and stem drug and human smuggling issues.
Same happens in Europe, but with North Africans and Arabs.