I was thinking not of just the UK but Europe as a whole. I think most European airports are publicly owned. How you define "publicly" will of course vary.
The UK is rather odd in many ways, with even ATC being privatised and as a result subject to all kinds of weird practices, like invoicing an airport for an approach radar service.
But none of this supports the case for PPR at so many places.
Customs PNR is more acceptable because one might not expect the Customs people (which, let's be frank, and as Croatia shows so clearly, is just one policeman) to be present during the full opening hours of the place.