Ever wonder why the police (except for Sheriff Joe) are so interested in catching speeders and DUI drivers, and not interested in picking up illegal aliens (which the TV news people call "undocumented immigrants")?
Could it be that the speeder and the DUI driver pay a substantial fine so they can go back to work? The illegal alien just gets processed, and has his day in court, before being deported so he can sneak back in later.
You can clearly see the problem. There is a cash benefit to the state, county, then the police, for catching speeders and drunks, but not for catching and processing illegal aliens.
If the federal government would reimburse a small sum like $2,500 to the state for catching/holding/processing an illegal, there might be enough incentive in these tough economic times, to induce state and local law enforcement to make catching illegal aliens worthwhile. It would be a lot cheaper than hiring and supporting additional Border Patrol and ICE personnel. It would also be a really cost effective way to help the federal government protect our borders.
It really does not look like a law enforcement problem, but does appear to be a simple matter of economics.