> I can sell my labour to many different companies with a relatively low switching cost.

Well, I disagree on this. Maybe you specifically can do it, but housing prices, healthcare costs, transport cost, family charges, etc, can make the cost and risk of switching prohibitive. Not to mention that "just switching" doesn't mean prices will be better. Just have a look at the latest stats on working poor people to imagine whether those can easily switch jobs and get better education.

> If the price of steel increased, building new mines to extract iron ore would cost great sums of money as well. It is not easy for all mining companies to do this. It doesn't mean that the market is not relying on price signals to coordinate the production of goods.

So there's a high cost of entry? That's very much a non-perfect market. A free market doesn't just "respond to price signals", that's a very low threshold as you'll hardly find a market that doesn't respond in any way to price changes. A free market has to respond to them in an elastic way.