[bryondowd]

It could be a factor, but probably not a main one.

I know first hand that there are organizations that will help people in poor countries get a tourist visa to a wealthier country, and set them up with under the table jobs for a few months so they can go home with enough cash to support their families for the rest of the year. Not legal, but relatively harmless.

I've heard stories, but no personal knowledge, of traffickers pretending to be one of the above organizations, but once the victim is in the foreign country, they effectively enslave them using some combination of confiscating their documents, direct threats, threats against relatives, and lying/exaggerating what the local law enforcement will do if they find out they came to work illegally. By the time people back home realize something is wrong, the traffickers have already moved on. No idea how accurate or how common this is.

Same would apply to orgs offering to smuggle people into a wealthy country without a visa with the intention of staying indefinitely. In either case, I suppose a freer flow of labor could reduce that grey market and therefore the opportunity for abuse.