There are still some protectionist issues on the single market itself.
For example, Poland defends its rail operator, PKP Intercity, against foreign competition by a series of dirty tricks, including "just never registering a sale of a depot to a competing corporation in the land registry".
Almost every major EU country, has implanted some domestic protectionist rules to protect some of its politically well connected lobbyist industries or jobs from cheaper or more efficient intra-EU competition buying them out. The restrictions almost never are in reverse.