This is a fair comment. The free market can certainly be made "better" (however one might define it) by certain interventions. Your example of weights and measures is a good one - the market benefits from an increase in knowledge of both parties in a transaction.

Another good example is FDIC insurance. We could have little to no banking regulations, but that would also introduce a lot of uncertainty and result in wild swings when the economic situation changes. Tell depositers that the gov't will back their savings helps stabilize the banking system which actually benefits the market (the same way a stable and predictable government/legal system benefits the market).