Allow me to give a slightly different perspective. When engineers are consistently outperforming their wage, I immediately recognize that with an unsolicited pay increase to match their performance. This has always been met with appreciation, as it demonstrates both that outperformance is actively recognized and rewarded, and secondarily that management is looking out for the benefit of the employees. This has positive cultural impact.

This is more or less difficult depending on the company. In a few cases, I had to go to war with HR to get a deserving employee a raise who deserved it but hadn't asked for it. Other companies have processes that are highly amenable to it.

In many cases, if employees have to ask for more money when they've earned it then it is a management failure.