As many things in the States, it only "makes sense" if you have been born and bred there and culturally normalised the absurdity of it.
No, tipping like in the States DOES NOT make sense, as it allows business to pay less tax and offer less protection to the employees, allows for less-than-living wage salaries to flourish, forces the employees to rely on customers' charity, encourages customers to be arrogant and abusive to staff "as they're paying their wages", encourages tax-free money which does not contribute to the common wellbeing of society and makes employees poorer, as they do not have higher salaries to show if they need to ask for a mortgage or a loan. It basically perpetuates social inequalities.
But hey, in the "land of the Free, home of the brave", pledging to the flag, having to mention God in every sentence, having no universal healthcare, defending the right to bear arms, ban abortion... all these things appear to make sense if you were born there. Oh, and they voted Trump as president and will likely vote him again. And they truly, deeply believe they ar the greatest country in the World, and always a bit better than anyone else. I stopped taking the USA seriously a long time ago.