- Wages often go over or close to the minimum anyway, due to market forces, and do so without costly bureaucracy/enforcement/taxation/distortion
- Minimum wages make everyone whose marginal value is less than the minimum wage unemployable (since you would choose not to hire someone for $20/hour if their marginal value is $15). This is disastrous for someone who'd love to work at $x/hour, but who lives in a state which legislates a minimum wage > $x/hour, since they go from being employed at a low wage to unemployed.