You are on private property - yes surprising no ? SMRT/SBS are private companies and to be exact listed companies. They are not a government agency or arm. The station - train, bus are on private grounds but you can access this as a consumer of the services they sell. If you are going there for any other reasons like filming, peddling or even distributing flyers you are there without permission (if you did not ask and get permission nothing to be said) you can asked to stop, detain and handed over to the police as trespasser. They do not have to give you a logical answer, another way to see this who are you to demand a reason ? Remember it is private property, so even a shareholder does not have that right save at AGM you can ask about this in the other matters section.
It is your tone of entitlement that makes me smile, as it is based on nothing but your sense of importance which the world never recognizes.
