For people to react so forcefully when their photos are taken, you can be sure they have in mind that the effect when the photo is out will be as great or greater.
These people have something to hide.
Sometimes... perhaps there have been rude and thoughtless photographers who have repeated pissed them off which results in their mindset against anybody carrying a large(r) camera round. I recall reading of an incident about a traditional wedding in a hindu(?) temple being disrupted by some jack*sses on a "photography outing"?
To make out a case under Section 3(6), do note that that it still needs to be shown that "it appears that his purpose was a purpose prejudicial to the safety or interests of Singapore."
Also, the proviso to Section 3(2) will still apply if you are trying to make out an offence for someone for taking a photograph of a prohibited place. Section 3(6) just reduces the burden of proof required, but does not nullify the provisio to Section 3(2).
But it still mean that anyone authorised is able to stop you from taking pics of prohibited place even if you are outside the boundaries, right? Since they can apply 3(6) up front and treat you as potential spy/terrorist until the matter is clarified.
if im not wrong i just read from newspaper saying no photography in MRT stations :P