Nationalisation of anything has no link with efficiency. The motive is to capture profits for the State. Profits follow investment. Why do you want your taxes to go into an activity which risk-takers are willing to address? What other State spend will you forego to liberate your taxes to do this?
If the buyer - an Airport Authority, an airline - is dissatisfied with a contractor's service, his remedy is to fire the individual (not poss. if he is a State employeee), or the firm (not possible....)