That's a completely subjective term that just describes that one part of the transaction does not like the deal that they entered voluntarily. That's why many people, including myself, consider the usage of this term an attempt at manipulation.
In almost any country where it operated or operates, Uber was not and is not a monopoly, neither on taxi clients, nor on labour. There are multiple taxi apps a driver can work for, and many shift between them in a span of one shift. And traditional taxi parks, although lost a significant market share, have not disappeared. Therefore, a price of a driver's labour is still dictated by an open market and not by Uber.
What changed, though, almost everywhere, is taxi apps made the market more fluid and effective, and turned over a lot of mechanisms which taxi drivers used to "exploit" clients. You just have to travel to a city that still mandates government-backed monopoly, like Istanbul, and compare the level of prices, service and reliability to what the ordinary Uber experience is like.
> Uber has essentially not just broken laws
Laws can be, and often are, immoral. And any laws that limit the ability of parties on the free market to transact with each other however they wish, including taxi medallions or similar systems, undoubtedly are.