“Africans from Africa are going to Mexico and then across the border illegally, how did they get the money to travel there?”
Air fares are cheap, maybe $700 total.
These people are often not “poor” by the standards of their country.
They might have a relative in Europe or the US.
They might have a parent with a good government job or business.
They might have a missionary friend or be under contract for “tax free” “low cost” domestic service.
Okay.
As they used to say on some game show “come on down!”
Or somebody elses (unknown) credit card.