It's fine to have no minimum wage, but then you need strong unions to ensure people get paid what they're actually worth. If you leave it up to the employees they will be at too much of a disadvantage.

Companies do everything they can to prevent market signals on what wages are worth so they can rip people off. Couple that with the fact that many people who are technically very good are not good at negotiation. A strong union (i.e. not what the US has) can help with these problems.