The way it usually works..the 'smuggler' is paid a deposit in Mexico. The smuggler brings the person across the border and to a safe house. The smuggler is then wired the balance by the family of the person he brought over. The smuggler then arranges transportation for the person to the state he or she plans to go.
Coyotes, or guides that smuggle people, usually do not just bring them over, let them free, and wait to be paid, then go back for the money.
Personal experience with people close to me. And all those people that came here that way are now card carrying legal residents, so don't get excited and call ICE.