Having endured school uniforms...
...I can say with some authority that they don't accomplish any of the money-related objectives adults say they do, because money will out unless people are regulated down to their underwear and required to have uniform haircuts. It works in the military, though.
They do, however, make it easy to identify kids from different schools in order to beat them up at the city bus stop, which is why we all kept civvies in our lockers in case we weren't taking the school bus home. Team mentality works both ways: to include and to exclude.