Without going off too far on a tangent or getting into whose system is better, from what I've been told, in at least some countries getting into a university is competitive - you need to test well. In the U.S., as long as we're talking about state universities and not the more prestigious ones, it seems it's not. In other words, in the U.S., yes you are responsible for your costs, but if you graduated high school or got a G.E.D., and you want to go to college, you can probably go. And many people who 'test well' qualify for scholarships, so college is often subsidized...if you're obviously high end college material.
Now, graduate and professional schools (e.g.: medical or veterinary schools), private or other 'big name' schools are another story. But someone who wants to go for a Bachelor degree in the U.S. can get the opportunity.