The asymmetries of power between both parties does not mean the contract is not voluntary.

Asymmetries can get to a point that some contracts might as well be involuntary. Not to mention that those that have the power can and will abuse it. To think that a person whose choices are "begging on the streets" or "dealing with all sorts of abuse to ensure food safety and shelter" has any real choice is wishful thinking.

In fact, any government intervention in the labor market will make this situation worse, as these encourage poverty and harm those workers who are the less productive in the market.

Wrong. Badly written and badly implemented laws can encourage that. Any decent law that forces companies to abide by safety and health standards are protecting workers from injury and possibly the customers from disease. Women getting harassed by horny bosses shouldn't be left to their own devices. Read that part about power asymmetry above. People with power will abuse their power. Laws should exist to ensure that they don't.

The difference is that having market concentration does not mean being a monopoly. In fact, a monopoly is a government-grant privilege, for gaining legal rights to be a preferred producer is the only way to maintain a monopoly in a market setting.

Wrong. You can have monopolies without any state. There are natural monopolies, like water and sewage, or roads and railways, these latter two to a lesser extent. In a lot of places, there are de facto monopolies of services like electricity or internet connection, the latter even being parodied in a South Park episode. Also, without a state, it is easy for a big enough company to collude with others to ensure local monopolies (oligopoly), or for it to harass or simply buy out any competition. The state is the only thing that can force a monopoly or oligopoly to end.

As much as you complain about government violence and coercion, that's the only thing allowing for any "healthy" capitalistic state to work. If you remove the state, then there's nothing forcing anyone to follow any sort of law. Therefore, stealing is not a crime. Impersonation is not a crime. Bribes will become "personal tax". As soon as a company has to pay a private security force to violently enforce what it wants, like the safety of its own resources, it acts no different from a state. Not to mention that there's the real risk of any company that sells "protection through violence" to decide that they deserve more, bullying everyone for money because, hey, fuck you, I have the guns, whatcha gonna do? Call the police?

Keep in mind that price manipulation is not exclusive to govt's. DeBeers controls the supply of mined diamonds, they set the price. A monopoly.

Anarchism can only realistically work when there's only one person. As soon as there's more than one, some sort of social structure is created. Capitalism depends on a state existing to ensure some sort of obedience to law and, if it doesn't exist, companies will step in, one way or the other, always looking to ensure they maintain their own power, obviously. Which, again, is no different from a feudalistic state.

“In a market economy, the range of quality, quantity, and type of goods and services correspond to social needs. These goods are services that are valued by consumers, and hence, they will be provided if it is economically feasible to do so relative to other social priorities.”

Wishful thinking. In a market economy, it's all about profit. If one can profit off cheap, plentiful stuff, they will. If there's more profit to be made ignoring lower density areas, then they can go fuck themselves for not being profitable. "Dangerous" areas can also go fuck themselves for being too poor/dangerous to be profitable.