I didn't have any ulterior motive behind not addressing your other points; mainly I just wanted to share my perspective on things that I actually have experience with. I'll take a stab at a response now.
first of all, mandatory tipping at a coffee shop or takeout place is dumb. afaik, these are not legally considered tipped positions and the employer is not usually allowed to count tips toward minimum wage. that said, I certainly recommend you throw a little extra in their tip jar if they actually provide outstanding service.
> Do you tip any of the people i mentioned? Because, frankly a garbage men's services are way more useful and needed than a servers. Why do servers deserve a tip and not people working at clothing store? Or people working at Walmart?
I don't claim that the tipping system is inherently moral or immoral. my claim is that it is a practical way to align incentives in a particular set of situations. in a restaurant, the difference between acceptable and great service is quite large. if I'm handling several tables, I'm usually going to get to the tables that tip well first. I'm going to make sure they're not in the middle of a deep conversation when I go over to check if the food is okay. there are tons of subtle things that a skilled server can do to improve your dining experience if they are incentivized.
garbage men, on the other hand, either pick up your trash or they don't. idk what the difference between a good and a great garbage collector is, maybe the great one takes the time to leave my can sitting upright? a cashier can ring you up fast or take their time, but can't really affect your experience other than that.
I do actually agree that maybe some retail positions should be tipped. I find that usually Walmart employees don't give a shit whether I find everything I'm looking for. occasionally one of them is super helpful and saves me 30min or more of hunting around the store. in these situations I try to slip them a couple bills. if they refuse, I make sure to find their supervisor on the way out and explain that they made the store a lot more money by helping me find my things.