Stock buybacks and wage increases are not necessarily related issues. A stock buyback is just a way to return money to shareholders. A wage increase is about paying your workforce appropriately. The only connection between the two is that they both involve a transfer of value from the company to a group of stakeholders but it is not as if the choice is exclusive or correlated.

Companies generally pay their workers more only if they have to (tight labor market, threat of stoppages, etc). Companies generally do stock buybacks if that is the best use of the cash at hand (ie there are no better investment opportunities for the capital available). The considerations are completely different.