Well, there are people who put their brake levers on all kinds of places, BSNYC features such pictures all the time (usually of fixed gear bikes), including behind the seat, on the top tube etc. Why people do that? Possibly because they don't know any better, because they cut the brake cables too short, because they think it's funny, to flaunt opposition to compulsory brake laws without risking getting a traffic ticket, etc.
(eta: and no, of course none of that are good enough reasons to do something so ridiculous)