When you think about it, tipping really is an irrational practice.
Nowhere else in the entire labor force does the customer have so much discretion in how an employee gets paid. The closest analogue is to stripping. Some strippers are employed essentially as independent consultants and therefore make most of their money from tips. Some salespeople work on 100% commission, but their pay is up to the employer, not the customer. There just aren’t many jobs where the compensation isn’t between the employer and employee. When someone makes a bunch of money for good performance, it’s a bonus or commission. But when you make $3/hr and have to serve food to assholes who only drink water and order the cheapest item on the menu then your bonus is a “tip”.
Yet there are so many people with similar positions in the service/labour industry that we do not tip. It doesn't take someone any additional skill or training or experience to land a job at Ihop Vs. McDonalds, yet we won't even consider paying those who work at those lowly fast food stations more...even though those businesses are booming with our hard earned dollars.
Tipping is archaic and uncomfortable. If I’m unsatisfied with my meal (at the fault of the server) I feel compelled to leave a lower tip but often don't in fear of getting on some blacklist of bad regulars that will have spit in their food.
Not only do some service positions get passed by on tips, but in some places the waitstaff are required to make minimum wage. Here in Washington state that is 9.19 hourly plus tips. So if I go to a restaurant it might take my family several hours of work to pay for that meal, including the tip, and yet our waitress serving us is making that in less than an hour. Unreal.