See my post about healthcare. Our system has been strung together with too many assumptions made. Our tax system, our healthcare system, etc would fall apart.

Now, I'm all in favor of tearing apart the retarded system we have and going with a more practical, minimalist approach which may work better with an open border (fair tax comes to mind, as one step in the right direction), but there's far too much political intertia against changing what's there. The government likes the system the way it is, even if its inefficient. It gives them a lot of power to modify and tweak things to win elections and hook up their friends and it gives them a tight control over everything. The only problem is that, the system itself is flawed, because its based upon many assumptions related to our tax system. Thats how we determine employment rates, wages, etc. If you suddenly took the fences down, the whole system would crash.