If companies published the average salaries for each job role (including by gender / other demographics, provided you can't identify an individual salary) that would eliminate any doubt.
As it stands lots of people think they are underpaid, given the ever rising cost of living, devaluing currencies, and that senior level salaries keep accelerating away.
I read somewhere that the difference between average US incomes and that of company CEOs is now approaching 1000 times, in the past it was only around 10 times. If you take into account offshoring of work to low cost centres, the difference between the highest and lowest salaries would be approaching 10,000 times! i.e. The highest earner probably earns more than the combined income of entire office complexes of employees in some parts of the world.
When they eventually replace all workers with machines, a sprinkling of CEOs and shareholders will own everything. People better rise up before they activate the enforcer drones.