Strange Going On's In Vegas, Kingman

Last Friday, I was leaving Las Vegas around 9:00 at night when I pulled into a Rebel gas station in Boulder City, just outside of Las Vegas.
In came ina bus, kind of like a tourist bus that we all see in Vegas, but this one was different.
The bus writing was all in Spanish and it had a Mexican license plate on it.  Out popped out about 40 Hispanic men, ranging in age from about early 20's to may late 40's.  None spoke English and there were no females outside.  Out of the 40 or so, maybe 3 actually spent money at the gas station, while the rest either went to the rest room our just waited outside.
Ok, I thought, strange but there may have been some kind of explanation:
45 Hispanic males on a tourist bus.
Huge bachelor party.
A bunch of gay Hispanic men leaving Las Vegas after some fun.
But I talked to a woman in Kingman, who saw the same thing at a Kingman gas station, which was on Hwy 93, the road heading north to Las Vegas.
This time 2 Mexican buses stopped at the gas station and about 80 or so male Hispanic males piled off and either went to the bathroom or made eyes, ogling my woman friend.
Apparently, these Mexican buses don't have bathrooms.
But this is something I have not seen previously or anybody I have talked to.
So, why are these Mexican buses bringing scores of Hispanic males to the Las Vegas area?  Where are these men staying?  Are they getting a fair wage, assuming they are laborers?  Who is employing them?  are they paying taxes on their earnings?  Do they have the necessary paperwork to even visit the United States, like a passport?  Are they here on some kind of Obama plan?
I honestly don't know, but maybe some news reporter can find out what is going on. (And I know some read this blog)