The federal minimum wage for tipped employees has not been raised since 1991. It has been $2.13 per hour for 23 years, which is simply ridiculous.
Yes, servers are tipped, but inconsistently, and sometimes not at all. This is particularly true in areas that get a lot of international tourists, because tipping American-style (15-20%) is simply not done in most foreign countries where the servers are paid a regular wage for their labors. Over the years restaurant owners have had servers do more and more of what used to be done by hourly, non-tipped employees simply because it's cheaper. (you rarely see bus boys anymore!) Plus, tipped employees are paying taxes on ESTIMATED tips and frequently their paychecks are actually zero because their meager earnings barely cover the taxes.