Ok, I get it, you don't like the 'wall' idea........ so how would you go about the 'illegals' issue ?
Complicated situation with a complicated answer. Most people that are here illegal got here on legal visas and just decided to quit college and never leave, or keep working after their work visa expires. They did not enter illegally. Nobody keeps track of that group, just focuses on the ones that come here at the border.
As for the illegal border crossing, well, if you were afraid that if you stayed in your country you'd be killed in the street and legitimately thought you'd have a better life in the US even with the known consequences of coming here illegally you'd probably do it to if it meant potentially saving your family.
It's like putting the guys that steals a loaf of bread to feed his starving family. What's really the issue here? Bad luck and bad circumstances can happen to anyone. We can't pretend that if they cross the border they are a criminal. According to our laws, sure, but a REAL criminal?
Another example is the guy that's in prison for some marijuana offence. Does he get to leave if his state legalizes marijuana? It was a crime, now it isn't. What then?
There are lots of questions that could be asked when someone "breaks" the law for what could be seen as a good reason. Taking an experimental drug that could potentially save your life used to be illegal. Now we can do that.
As I said, not a simple question, no simple solution.