Exactly why is it considered rude to EXPECT tips from (paying) customers?

Because that’s how it goes in America. In my country, we shove our cultural norms down your throat, whether you like them or not. Oh, if you dare not participate in any of that, then fuck you. You’re an evil, cold-hatred monster.

Edit: So, I did some rethinking about my original answer....

Admittedly, I hate how I’m forced to tip others simply because it’s the norm. HOWEVER, I do believe the tip you get should depend on how well you’ve done your job. I usually tip maybe.... $2 at best. Might give them $5, if I’ve had really great service. But I just hate the idea of tipping just because I “have to”. It’s annoying AF.

Idk tbh. Tipping isn't a thing in my country.
If I ever went to America I wouldn't even know how to tip lol. It's just a foreign concept to me.

never heard of it

Because in certain places, customers don't have to give tips and your expecting them to give up money they worked for.... maybe?

If you're working hard at a restaurant or just working hard in general then yeah, expecting a tip shouldn't be considered rude.

The only time I ever considered it rude was when me and my sister (10 and 12 at the time) went to a restaurant and the waitress gave us attitude for not giving her a tip when that was all the money we had. If you're gonna get mad at kids for not giving you money then you're a real dick

link and link

The US is the only place I can think of that does tipping (though there may be other places), and imo there is something very wrong with the tipping process - that is that employer isn’t paying the employee enough money so that they must rely on the customer. In europa it’s common that they just get higher paychecks so that they don’t need tips. America’s system is pretty broken if you ask me. But I still tip of course, because until it’s fixed that’s what the employee needs.

As to your first question, (considering you’re in America) it’s probably because the customer likes to think they have the power and that it’s their generosity that is giving the tip, despite it being common practice. Also for some reason it’s just considered rude to talk about taking someone’s money. Basically I think since the customers doesn’t technically have to pay the tip, they want you to act grateful rather than expectant. Honestly I don’t really blame the customer or the employee in this situation. It’s just that tipping is so weird.

Because capitalism???

Honestly I think it's annoying that some places won't let people accept them. If you did a good job, good enough to earn a tip, then you should be able to take it.
Like I worked at a place where I arranged balloon bouquets; it's time consuming and tedious because some people get ridiculously specific. I was told that I did a good job and that they really liked how I did it. I was offered tip money but, per company policy, had to decline. It was annoying as fuck because I clearly did something right, I clearly went above and beyond and I wish that I could have gotten the reward based on good merit.

In some work places tips are literally a person's livelihood; the company pays under minimum wage claiming that tip money makes up for it. Which imo is bullshit because there will be days where no one tips and that can crush a person financially. For that reason alone people shouldn't consider it rude to expect and accept tips. Tbh I think they should do away with tipping and give staff at least minimum wage and then if people want to tip still, they can. But there's less pressure on the customer and the employee has some mais stability.
But this is just my take, I've never worked a job where tipping was essential like that so I could be wrong.

Now I can see it as rude to expect tips if a person is only doing the bare minimum or a below average job; in which case they are basically expecting something for nothing. But I feel like most people don't do this.

It's not.

In a lot of cases (such as with servers), workers make less than minimum wage and tips are the only way they have enough money to pay for food, rent, etc., like zanhar1 said. The amount you tip depends on how well you think they did their job.

About a mês atrás I went out to eat and ordered a simple x-burger, cheeseburguer and fries. I felt that getting change back was unnecessary so I let the server keep the extra 5-10 bucks on topo, início of the tip and she was so grateful even over such a small amount of money.

It's not rude to expect tips. It's rude to not tip.

We tip in my Country as well though it is mostly a gesture of gratefulness from the customer side for a job well done. It's not like it's being seen like a tradition, a custom or anything of the sort. I haven't really seen any Employer actually waiting to get tipped so far honestly. That being said, it is clear that there are those who hope as they try to provide you the best possible service. I do not see anything rude in that. Especially if you go out of your way to place greater care for a person or the paycheck just isn't enough for the amount of work you have done. NOT tipping in this case is what seems pretty rude to me XD It's always good showing appreciation in every aspect of our lives so yeah, there is nohing wrong with the practice of tipping ITSELF !!!!

In my country tipping is not mandatory, but people still do that most of the time. I usually tip accordingly to the service and price I pay. I`ve been out with a friend and he was like 'I`ll cover the bill', but then he said that he doesn`t wanna leave a tip, just because he doesn`t do that in general. So I left it instead. But it`s mais like the waiters are happy for that extra money rather than getting angry if they don`t get anything.

Tips are usually only expected from customers who pay with intercourse so I wouldn't know