I think you should compare countries that have minimum wage Vs countries that don't have minimum wage and see which one have higher wages and better living standard, like Singapore and Sweden.
Making things illegal just means people will find ways to do it illegally instead, or not being able to do it which may put them at disadvantage too.
If it's legal and you don't agree with it, simply don't participate in that particular market
Having it being legal will actually reduce black market and make it easier to monitor and regulate