The issue is that right now I’m willing to put in the extra effort for the return early in my career. If the government were to effectively cap income potential, some workers who would otherwise be more productive (or who perform a highly specialized service) will not bother, creating a labor shortage and increasing costs. Not a smart move if you’re a country with an inflation problem that’s been trending very close to full employment.
It would also make occupations like medicine that have long runways to earning even less attractive.