PMI

So I was thinking this morning that PMI is really stupid. A loan company charges PMI until you have (I think) 33% of your loan paid off. It's their way of getting something from you if you end up going into foreclosure. What I don't get is why they get to keep the money. If you were to rent an apartment you generally pay first and last months rent, that way the landlord doesn't get screwed if you decide to up and leave one night. Why can't PMI do the same thing? We'll keep this PMI for you until you have 33% of your loan paid off and after that we'll give that money back because you've proven that you haven't gone into foreclosure and you're more likely to finish paying off the rest of the loan.