"Those who cannot remember the past are condemned to repeat it." - George Santayana
That, or they’re politicians who do things they know perfectly well are doomed to failure because they have a personal interest in doing them (like taking payoffs, getting re-elected, servicing big money supporters, getting laid by prostitutes, etc.)
That’s why American taxpayers are being forced to build a worthless wall along the Mexican-American border. The laughable monstrosity isn’t even fully built yet and it’s already failing.

A recent article is proving yet again that real people are smarter than politicians. Smugglers and illegal immigrants keep defeating the fence. They establish new routes around it, build ramps to drive over it, dig tunnels under it, blow-torch holes through it, cut down metal posts acting as vehicle barriers and replace them with dummy cardboard posts.
And our own engineers can’t even keep floods from washing it out.
What exists of the wall right now requires regular repair. Bet that ballooning expense wasn't factored into any accountingcrat's budget. Unintended consequences, you know.
People who read history already knew that the Mexican boondoggle barricade wouldn't work. Here are a few examples of failed walls you can post on your MySpace wall:
Berlin wall A tourist attraction today, it once did a good job of keeping East Berliners in East Berlin. It failed because the wannabe socialist superpower, the Union of Soviet Socialist Republics, fell. It rotted from the inside out, much as the United States of America will fail once it reaches the ruling class's wet dream of becoming yet another socialist world empire wannabe. Once the Russians withdrew their occupation troops German citizens simply chipped the wall into rubble and sold the pieces as souvenirs.
Walls of Jericho According to irrefutable Biblical buzz it toppled with a few choice blues notes blared by a horn blower named Joshua.
The Wall, Pink Floyd Didn't keep anybody out. Everybody got high together.
Hadrian's Wall The Romans couldn't conquer and control the land known today as Scotland so they built Hadrian's Wall and, further to the north the Antonine Wall, to keep the clans from attacking their British provinces. The walls didn't work so the Romans resorted to a much better, time-proven method: they bribed the tribes to keep them out.
Great Wall of China The Chinese rulers spent several centuries, fortunes, and lives (some historians believe one hundred million laborers were simply worked to death) to build the biggest, baddest brick pile in the history of walls. So what did the Mongols do once they decided to get serious about conquering China? They bribed the gatekeepers to let them through.
As far back as 2006 the Washington Post was reporting persistent bribery at the Mexican border. So add greased palms to the ramps, route-arounds, tunnels, blowtorches, cardboard columns and flooding foundations and what you get is a relentless pattern of failure.
The Great Wall of Mexico will never be more than a speed bump. It will keep out a few people on crutches and walkers. It will be mostly forgotten by history. It simply doesn't matter whether you're a bleeding-angst liberal or a xenophobic conservative or a freedom-for-all libertarian, history proves that walls don't work.