When you raise the lowest level it cascades upwards too- does anyone else but me see a correlation between the huge increase in the last minimum wage (15% raise!) and the current rising prices?
Leftwingers push the minimum wage because their union thug supporters base their scale off of it.
Also, it panders to the class envy aspect that they always play to.
Statistically, very, very few actual people stay in the bottom quintile of income earners over time (more move in from the bottom - immigrants & teenagers).
And this number is even smaller if you limit your study to those that actually work nearly 40 hours a week.