But what if that rate of pay is more than the new employees are worth to the company, so hiring them would not benefit the company at all? Then it's not a market rate, because market rate isn't just the outer edge of what one side finds acceptable. If both sides don't find the rate acceptable, there's no market rate.
If a "greedy" employer refuses to pay what it takes to hire all the people they need, while their enlightened competitor does pay what it takes to get the necessary additional labor, one of those employers will have higher profits than the other, and the one with lower profits will be pressured by their investors to become more like the other.
That has been going on for centuries, and the result is a "labor shortage" in some areas, meaning companies (that always face competition from other companies) can't get all the labor they want at existing rates and wouldn't benefit from additional labor at higher rates. The problem may well be gradually driving the company out of business, but still, raising their wages would just drive them out of business faster.