What makes capitalism different is that the power is distributed along capital (as opposed to handpicked by the king under feudalism; or embedded in government monopoly under mercantilism).
In other words, in capitalism, the owners of capital (or the owners of the means of production; i.e the rich; the aristocracy; etc.) are the ones who get to dictate the living conditions of the rest of society. The rulers (be it democratically elected government; an absolute monarch; a military dictatorship) will legislate in order to maintain the interest of the owners of capital. The police (or military) will fight for the interest of the owners of capital, and will suppress any resistance against the interest of the rich, etc.
Full laissez-faire, free market capitalism generally leads to wealth (and power) imbalance. Regulation is necessary to prevent that (assuming you want to maintain a "fair" democracy of sorts and not regress to oligarchy).
The problem is that extreme wealth imbalance leads to a power imbalance that tends to throw society into turmoil. The French Revolution being a canonical example.
Even if they perhaps work the same number of hours a year, Maria has more training and (maybe) some kind of rarer aptitude and as a result we have a lot more house cleaners than neurosurgeons (in america and other places there a whole bunch of other factors like who gets access to the training and so on that causes some of these imbalances, but that's a whole 'nother comment).
The people, in general, are probably considerably less happy with the idea that jk rowling the ultrarich author gets to use her money to try to pass laws taking rights away from people she doesn't like.
Look at the difference between Ellison and Musk. Ellison is probably has similar levels of power to Musk, but he (afaik) mostly uses it to buy giant yachts and annoy other fortune 500 companies, and as a result most people don't really care that he's a billionaire.
Musk, on the other hand, tries to use his power to screw with government services and publically attack minorities and so on.