After they go home they can apply to LEGALLY immigrate to the US, then they can work, own property, drive cars etc. LEGALLY.
Before Mexico became as dangerous as it is lately, that is exactly what was happening. People were going home when the economy tanked and work dried up. But...
Now there are kidnappings going on down there. Anyone that was in the U.S. and banked some money has a high likleyhood of being held for ransom.
Families that get money sent to them from the U.S. are having a family member kidnapped and then a message is sent to the relative living in the U.S. to send payment.
It is going to take much more incentive than whay you point out for them to want to go back home.
You also forget one significant point - many people do. They are not just the employees. They are the employers. The days of Mexicans coming here and taking meanial jobs are long gone. They are you pool repair and supply company, the company you purchased your satellite service from, the guy that sold you your furniture, that owns the company that supplies pallets to you company...you name it.
That is a long, many year process.