The "why not $20" argument is moot right now, if we are allowing unlimited immigration. If blue states raise their minimum wage to $15/hr, and the red states don't, where will the immigrants move to to get jobs? Are they worth $15/hr? No, they will settle in red states with lower minimum wages. Then they will start voting, and soon the red states will be Venezuelan bolivar states.
Raise the minimum wage, and replace the income tax with sales taxes in red states. This will raise the cost of living in these states, and they will move on to blue states.
These things are under state control, not federal. Rather than just complaining, this is something they can do.
Most states already have sales taxes;some more onerous than others!
Since ILLEGALS will just go on welfare and/or get paid “under the counter”, raising the minimum wage is dumb. And why wouldn’t they move to where the minimum wage/the welfare payments are higher; which are BLUE states?
I don’t think you really though this through.