Isn't the whole point of modern free-market economics that voluntary exchange can never be zero-sum, since both parties generally benefit in such exchanges, else they wouldn't make them?
The addition of government coercion wastes resources in (at least) two ways:
1. By forcing people to make decisions they wouldn't otherwise make (i.e. decisions that don't benefit them)
2. By generating a massive bureaucratic apparatus (both in government, and, for compliance, in private business as well) which generates nothing but must contain and support people, who, by definition, consume already scarce resources.
I'm honestly not worried that "the oil man" will force me to buy his oil. I want his oil, as its use (at current prices and my usage levels) makes my life better. I am, however, worried that the government will put a gun to the oil man's head, and make him either:
(a) not sell me the oil I want, or
(b) extract a "We don't want oil to be viable" tax from him, making the price he must charge me to profit too high for me to afford, forcing me to grudgingly curtail my use of oil (and funneling the tax money he does get to create larger bureaucracy, more regulation, and thus further negatively impacting my life).