1. There is a finite amount of “better jobs.” This is the reason that you have overqualified people working in low pay jobs. It’s called “underemployment.”
2. Not everyone has the time/money to get more education/skills/training. Especially when they are working full time on starvation wages already.
3. Someone still needs to work that shitty, underpaying, unsafe job. And those people will also deserve fair pay and safe working conditions.
4. This is why we need labor unions.