Until the early 20th century, Americans viewed tipping as inconsistent with the values of an egalitarian, democratic society.[83] Also, proprietors regarded tips as equivalent to bribing an employee to do something that was otherwise forbidden, such as tipping a waiter to get an extra large portion of food.[83] The introduction of Prohibition in 1919 had an enormous impact on hotels and restaurants, who lost the revenue of selling alcoholic beverages. The resulting financial pressure caused proprietors to welcome tips, as a way of supplementing employee wages.[84] Contrary to popular belief, tipping did not arise because of servers' low wages, because the occupation of waiter (server) was fairly well paid in the era when tipping became institutionalized.[84]
In spite of the trend toward tipping as obligatory behavior, six states, mainly in the South, passed laws that made tipping illegal. Enforcement of anti-tipping laws was problematic.[83] The earliest of these laws was passed in 1909 (Washington), and the last of these laws was repealed in 1926 (Mississippi).[83] Some have argued that "The original workers that were not paid anything by their employers were newly freed slaves" and that "This whole concept of not paying them anything and letting them live on tips carried over from slavery."[85][86]
Sounds like could be a bit of both, and more evidence is just something that is outdated now really. ---