Having "no fixed hours of work" is a social class signifier in many cultures.
But you are right some one getting paid 250k is still a worker and does have "labor" issues just as some one on 25k does.
Obviously issues may present in different ways for high and low paid workers
On the other hand, there are also high-status professionals, like lawyers, who bill by the hour.
I think one advantage of being paid for every hour of work you do is that whoever is paying you is going to be less likely to burn overtime hours on meaningless things. For example, that arbitrary end-of-month deadline you're working on doesn't look nearly as urgent to the business if they need to pay for the night and weekend hours required to meet it. If the company knows that each of your hours is valuable, they might even treat you with more respect.
There is also a LOT of sharp practice in legal billing