Who would decide this relative level of moral worth of the various roles? How would you compare the value of a scientist to a firefighter to a teacher? And how would you mandate what private companies can pay their staff? Or do you propose that if we, say, decide a doctor is worth more than a banker then all doctors should have their pay raise above that of bankers and additional taxes should fund this? How would you restrict the earnings of self-employed people to what you think they "deserve"?
What you propose is completely unworkable. Pay reflects the scarcity of the skill/ abilities/ experience necessary to perform the role, plus the value added economically, although obviously this is subject to distortions when public sector pay is artifically reduce by Governments, or artifically inflated by union activities.
It's also very difficult to compare because you need to consider pensions, likely retirement age, working conditions, and hours as well as headline salary.
What is interesting is that sectors which are male dominated are generally better paid. There is evidence to show that when more men enter a field (e.g. IT/ tech which was originally female dominated) pay increases, and vice versa. This may be due to cultural biases, as well as the fact men are generally more aggressive with negotiating salary rises.
Ultimately the best thing to do would be to focus on improving the economy so that the wage stagnation that has dominated the last two decades is ended and salaries can rise sustainably above inflation, raising living standards. The only way that can happen is through productivity increases (the UK is woeful on this).