Now that’s a little simple. What you mean, I guess, is that operating in a free market economy facilitates private initiative, which tends to produce more wealth than other economic systems could, and that a lot of what we are used for as citizens of first-world countries could not exist if our countries weren’t wealthy. I’m not an economist, indeed, I don’t know a lot about the subject, but I think that’s about as good an explanation of capitalism as there could be. And I would agree that this is one of the advantages of a free-market economy.
But on the other hand, I consider a free-market economy, and indeed, any economy, to be more of a tool that we use to try to improve our condition as a nation, and in an increasingly globalized economy, as a world. I don’t worship capitalism, and I don’t have any moral problem with adding constraints (such as labour laws, for example) to ensure that our tool does what we want it to do. Companies, as you said, have a duty to try to make as much money as they should, without regard to who or what they harm in the process. So it is our duty (through our governments) to prevent them from doing too much harm. Companies make money and create wealth, like they should, given that that’s what they’re good at, and the government protects its citizens and the world they live in, like it should, given that’s what it’s good at.
As for labour unions, well, I’ve been an officer in my union (which is a teaching and research assistants’ union at my university) and I’ve left with a good impression of the work they do. We generally have good working conditions, but some departments don’t always respect them, and most of the union’s work is to bring those departments back in line, hand in hand with the employer. Unions should try to improve their members’ conditions, and I believe that it’s what most of them do. There are bad unions, who don’t defend all of their members and who, for example, buy booze with their dues and defend only a few buddies of their president. There are bad companies, who break the laws that they have to respect, or who lie to their stockholders. In every economic system there will be bad actors. But I think that it’s possible to reach a balance, and I absolutely believe that labour unions are still important in today’s world.