As Jim Kunstler points out, the Postal Service is mandated by the constitution. Food stamps are not.
Speaking of the constitution, Im getting a little sick of these corporate CEO knuckleheads who come on CNBC and complain that the US Postal Service is running at a loss, and therefore we should abolish it. There is actually little beyond all those post offices that holds the fabric of small town America together anymore. And anyway, delivering the mail is one of the few actual government services that is spelled out in the US constitution in no uncertain terms in Article One, Section 8. It doesnt say the postal service must run at a profit, by the way. The food stamp program is not spelled out in the constitution and it doesnt run at a profit. Neither does the war in Afghanistan if you dont count the drug money. Congress runs at a profit, but not in any way that the constitution provides for. Before long, a lot of people are going to want to abolish it.