I'm not saying that it's only spotters, but there is a small element within the hobby which seems to think it's OK to do it (as there are with those flying drones too close to aircraft, and with those who take a 'souvenir' from an aircraft in a museum).
I know for a fact that BTP issued a memo to officers working around airports to be on the lookout for people pointing anything other than a camera at aircraft (which specifically mentioned checking 'spotters areas').
True, but there's still an selection of aviation enthusiasts and modellers who seem to think that air museums should be their private property, on which they can do as they like, and that the 'Great Unwashed' should be barred.