Most jobs don't have tips. People working in them still manage to do a good job and many of them make a lot more than people in tipped jobs do.
In reality, it’s a gesture of pity for those who earn little, and who we don’t want to pay properly via decent wage regulations and increase product prices, but we want them to dance for us and have them hope we will toss a few coins their way. In the process, we get to feel good like benevolent dictators who have chosen to be generous and share their wealth.