Those are bullshit claims.
Everytime I've gotten pulled over, without fail, I've had a exchange that went like this:
Officer: Where are you from?
Officer: Where are you from Originally?
Officer: I mean, where were you born?
Me: San Diego!(thinking: You Fucker!)
All because of a speech impediment. Now, as pasty as I am, it's going to be a million times worse for someone a few shades darker. And if I may indulge in a little stereotyping for a moment, nothing is preventing the cops in Arizona going to Home Depot and harassing Day laborers...or the people who are hiring them. I imagine this is giving the Border Patrol a huge woody. While most Border Patrol officers are, I'm sure, hardworking and honest, my direct interactions with them have been uniformly negative. While local and state cops tend to take into consideration that they are serving the public, and maybe they shouldn't be assholes to everyone they come across, as far as the BP is concerned you are guilty until proven innocent.