With regards to the issue of our southern border, and the importance of keeping it secure from illegal entry, we wouldn't have this problem if our leaders didn't really want it. The INS presence along our border is nothing more than grandstanding to give us the impression something is being done about the problem.
One cannot fault Mexicans for their desire for a better life for themselves and their families, and they see the US as we advertise ourselves: A land of opportunity(I have issue with their seeming inability to rectify their lot in their own country, but that's another rant.).
If you look into the problem, you'll find there are extremely minor penalties for employers who hire illegal aliens, even if they underpay them by our legal standards. Employers find it a small risk to hire illegals as a result, and therefore continue to do so.
Applying simple logic, if the opportunity was taken away, there would be far less incentive for illegals to come across, because there would be no way for them to get income. The schools, medical availability, etc., are all secondary to their drive to enter the US. If stiffer penalties were levied against employers who hire illegals, they would at least think twice before engaging in the practice, and I believe we would see the tide stemmed, at least somewhat. However, big business continues to want cheap labor, so we will continue to see our tax dollars wasted on INS agents futilely flailing away, trucking illegals back across the border so they can turn around and repeat the process.
I once worked for an employer who suddenly began hiring illegals to work in his warehouse, paying them $4.00 an hour cash(I recall the minimum wage at the time was ~$5.75/hr). Between his domestic help and the warehouse workers, he had 9 working for him at one time. I called the INS and reported him, and they said they'd get right on it. Three weeks later, nothing had happened, so I called in again to check the status. The report was "lost", so I re-reported it. Another three weeks, still nothing, so I called again. This time, the agent on the other end was quite frank with me, explaining that if they acted on the report and busted him, my employer would receive a maximum of a $250 fine per infraction(per illegal employed), nothing would be done to him for underpaying them, and the illegals would of course be deported. As a result, the INS generally sees little use in taking action on these reports, so they "back burner" them. He then said it would be useless for me to re-report it again, so I didn't bother.
All we have to do is take away the incentive for illegals to come here, and the flood would at least slow down to a trickle. But that's not what the people who call the shots really want.