The problem is that it's the norm in the US. If you have a service job (waiting tables, delivering pizza, etc) that's just how it works. You'd have to change the type of work you do because it doesn't differ much between employers.
Aren't there any unions for the these kind of jobs?
It's very hard to unionize. I ran a pizzaria for about 10 years and was the owner operator it for another 5. The employment length of tipped employees typically is around 6 months. With people coming and going so quickly, it's hard to develop the bonds that allow such organizing.
For positions filled people that are completely replaceable in hours, including finding and training them?
The answer might be obvious to you, but it is not to me. That's why I asked..