IMHO, there are really no rules, there no technique and surely there are no ecthics that specificly caters to street/candid shot.

its rules, technique and even social ecthics are just the reflection of the surrounding society.

too deep...? .

in layman term, we make the rules, we consider which techique is suitable and we will use the method that are acceptable to us in getting the picture. surely some of it will change overtime but currently we will used what best for us.

In a way when enough influential individual on the subject agreed on the same thing. Thats the rules.

rules of today may not be suitable for future used.

thats sociology.