If you're in public, you're fair game to be photographed. This should not give the photographer a license to harrass anyone, and like someone else mentioned, if a subject objects strenuously, I usually honor their refusal (I'm a hobbyist, not a PJ).

Keep on using those $1.00 (1.80 pound-sterling) words, Roger. Someone's got to look after the Queen's language.

Your point about the present becoming the past is especially well taken in this context.