Referring to the UK:
AFAIK there is no restriction upon photography in a public place. The police may try to tell you there is but they are wrong.
Inside an airport or aircraft is not a public place and the owners may delegate an employee to forbid the taking of pictures. Normally, in a UK airport, no-one will stop you taking pics of your dearest looking like death as they arrive from an overnight but I was once told to desist by some idiot jobsworth. "Oh, sorry, I didn't know." (You stupid ****)