The scale is different in both absolute and relative terms: 12 million persons = ~3.7% of the entire population (legal + illegal).
Simple changes to the law could force most to SELF exit the USA.
Fine any employer who knowingly hires an illegal 100,000.
Fine any person who knowingly rent to an illegal 100,000.
Fine any person who knowingly feeds, drives, enables an illegal 100,000.
GIVE a reward for $10,000 for anyone that turns in an illegal.
And make it very easy for them to leave. Maybe even give them $5000 exit incentive, and/or a chip, so we get radio pings if they ever try coming back. Is it really that unreasonable to put a low-jack on a criminal to make sure they don't commit that crime again?
That 12 million number will start shrinking very quickly. We wouldn't be putting 12 million people in handcuffs. Most would just drive out of here. They could start applying LEGALLY, from mexico, not from here. And we could set up some mnfg/housing towns right across the border to help with the transition. MEX would love the boost to their economy.
Above all - these people ARE breaking the law. They are. No denying there. There's nos such thing as "ONLY Kick out the illegals that are breaking the law" - because they ALL are.