Yeah, most "just put a wall up" or border patrol stuff is just political grandstanding. e.g the Australian example is that 96% of illegals come on planes, not boats, yet the government makes a big deal of intercepting boats and locking up the boat-comers in camps. If you came on a plane however then seek asylum then basically none of that happens to you and you're just allowed to hang out in the regular community while they do your paperwork. e.g. the "tough" system turns a blind eye to 96% of illegals, picking on only the weakest and most visible.
e.g. recently Australia hosted the Commonwealth Games, and ~255 of the athletes and visiting officials have escaped into hiding in Australia (edit: there were a total of 8000 people, so it's a fairly high rate). They're mostly from places like Nigeria. Since they're Visa overstayers, those ones won't be herded into camps like we do to e.g. Rohinga refugees coming on boats from Myanmar. And the most appalling thing was Australian Prime Minister Tony Abbott, who'd built his whole campaign on anti-refugee sentiment, suddenly did a 180-degree turn and said he'd invite in (I think) 10,000 Syrian refugees. I thought that was an odd reversal for someone like him who was so virulently against refugee boats, then literally one week later his own party voted him out of the leadership. So in other words, the tough-on-refugees guy who only cared about the "good of the nation" was suddenly heavily pro refugee if he thought it would allow him to cling onto personal power for a little longer.
Trust me, none of those people like e.g. Trump, but he's not the only one, give the first fuck about how many Mexicans their are, illegal or otherwise. They only care that you (you in general, not anyone specific) are dumb enough to care. After all, if someone else doesn't have the proper paperwork, but is living and working in America, it's far more their problem than it is a problem for anyone else.