Why does Congress get the money?

Why can Congress vote for it's own pay raises? Doesn't this seem rather strange? This would be like working at Wal-Mart and all the employees voting to increase their wages without Wal-Mart having a say in it. This is not the way to run a country. If Congress feels they need a pay raise, why don't they put it to a vote of the people. WE run this country or WE are supposed to. Shouldn't WE decide how much Congress makes?