But back to your question about what happens when employers lower their wages to $2 per hour, they would probably lose all of their employees and have to raise wages if they want workers. Believe it or not, wages do correspond in some way to the amount of benefit an employee brings to a company.
Lets say you want to hire someone to clean your house. How much would you have to pay in order to attract someone with enough skill to do the job? You couldn't just say you'll pay $0.50 per hour and magically get people to clean your house at that rate. There might be some people you'd attract for $5 per hour. As the price goes up, so does the pool of people you could pull from. However, above a certain price, it isn't worth it for you to pay someone else to do it. You might do it yourself or just live with it being dirty.
If having your house cleaned is worth only $5 per hour to you and someone is willing to do house cleaning for $5 per hour should you be allowed to hire them? They probably aren't going to be willing to work for $5 per hour if they can make $10 per hour somewhere else. Does it make sense for the government to say, "You can't hire this person unless the value they provide is greater than $7.25 per hour"? I don't feel that benefits you or the person who you want to pay. I don't feel it benefits society as a whole because I think we benefit by having money flowing through more hands not fewer. Minimum wage says that transactions below a certain hourly rate are not allowed, so it prevents money from flowing through some of the hands that might get it otherwise.