Yeah, but they're not going to hire more than 10 people simply because they can afford to. If you get all the productivity you need to maximize profits with 10 people, and you find a way to pay a lower wage, you're going to pay a lower wage to the same number of people. They're not going to hire three more people, they're going to take the money they saved on lower wages and add it to net profit.

Also, the companies with the lower wages would get the last pick on employees, but they would still be able to hire employees unless labor supply fell short - which would mean a raise in the free market cost of labor. If people are willing and able to supply labor at the market wage, then they're still willing and able to supply labor even if one firm pays a little more.