[Former Proud Canadian]

"How did these people get into the country in the first place?"

I'll take a stab. They got visas. They got on a plane. They overstayed their visas.

[Cowboy Bob]

Why would the USA hand oit visas in the first place?

In Russia, to get a visa to the US, you need to have a job, own property, and show that you have a reason to return to Russia. For young, single people, it is difficult if not impossible to get a visa.