Homeland Security Property Seizures
One possible explanation as to why Border Patrol agents prefer to profile travelers on public highways as opposed to apprehending illegal border crosser's at the border may be due to the fact that the latter are usually not driving in vehicles or carrying much property that can be readily seized and forfeited in order to augment Homeland Security budgets.
Asset forfeiture practices have become big business for big government and a recent report titled Policing For Profit put out by the Arizona based Goldwater Institute sheds some light on these policies as practiced by Arizona law enforcement agencies.