Are state-owned businesses inefficient?

Yes and this has to be the best proof yet:

States suffering through tough times are reaching for a tonic.

Lawmakers in several states with tight control of liquor sales are considering legislation that would shift the job to private industry, saving money and raising revenue.

If the government is maximising profit then it gains nothing from selling off its stores. The fact that some States in the US are thinking of do so suggests they know they are not running these business efficiently. If they can both save money and increase revenue then something is very wrong with the way the firms are being run now.