mexican workers are some of the hardest working people you will run across. i have delt with them in the construction trades like drywall. they come in and do backbreaking labor at a reasonable cost.
i don't know if your average american objects to the illegal immigration. people are just too lazy to work and even too lazy to think things through. if you live in CA than you are probably too lazy to mow your own lawn so you pay $100 to a mexican dude and happy because you saved $100 compared to hiring an american. it does not matter much to you that you are actually losing $200 on car insurance and $300 on health insurance due to the illegals.
the california produce industry would die without mexicans. who else are you going to get to spend all day stooped over in the hot sun picking strawberries?
It already is too late to build the wall. The Chinese built the wall to keep out the Huns, Mongolians, Khitans, marauding nomadic kingdoms but by the Qing dynasty they had already stopped building it as the Chinese imperial army had already conquered and incorporated northern territories far beyond the wall.(I think they even went as far North as Vladivostok, today home to the Russian Pacific fleet) Except in the USA, this is the reverse...... stealthily mexico has already spread beyond the border...We are now them...muahahhaha. Mexico came back to reclaim its lost territories.
Criminals! - instead of them working on their football and boxing skills during that time. BTW I agree with the idea from the OP completely - why don't we do it?
The Great Wall of China was a general failure in its time, as anyone familiar with its history knows. The invaders would attack at spots between the manned towers. It was mostly a psychological thing, not a true serious defense
illegal immigrants provide cheap labor for the large part, and they are the only labor when it comes to heavy/dirty work in construction, restaurants, retail labor, etc etc. I haven't seen a single white dude digging a hole in the backyard for a deck construction in my life. I live in the suburb of DC, so why wouldn't a contractor use cheap but most valuable labor sitting around? If we built a wall across our borders, it would eliminate some illegal crossings, but there are other routes to get into US. And if our soldiers guarded the borders ever so tightly, it's more tax dollars for you and me. plus i don't think americans become soldiers to sit around in the hot sun for months.
those soldiers could have been put to proper use to dig holes in this fine country had they not been sent to be killed overseas.