It’s pretty much because here in America, a server is fucking lucky if they make minimum wage at all, and minimum wage here is, what, $7.25 a fucking hour?
Some restaurants will only pay their servers a few dollars an hour, so they are basically kissing your ass to make ends meet. And if they ask for a pay raise, they are very likely to find themselves on the street unemployed.
And in some companies, they pool the tips between all employees, meaning that not only are you making maybe three bucks an hour, but if someone does a shitty job and doesn’t bring in as much in tips as someone else, everyone gets screwed.
It may be different in your country, but please, if you visit the US, tip your waiter if they do a good job. No, you aren’t expected to tip if your waiter is an ass (though I usually leave a few dollars because I never know which places do the pooled tip thing and I refuse to screw the others out of some cash-you can always speak to the manager if your waiter is a dick). Some of them literally make ends meet this way.
It’s true that some countries see tipping as an insult, but most states in the U.S. you don’t even need a reason to fire someone and it’s illegal for workers to form unions. So yeah, just asking for better pay is reason enough to get you thrown out without question. “Right to Work” states, my ass.
I currently work as a server in three restaurants at $2.83 an hour. Technically, if your tips don’t add up to at least minimum wage, they have to compensate you on your paycheck, but most restaurants do not, and inquiring into it will get you fired on the spot.