OK, took a bunch of different MRT lines today, only that one station (Guting) said to use both sides. People still standing to the right.
As someone else said, there is a special place in hell for the people who run in front of you and then stand on the left (usually on the phone). I had a 9 or so year old boy do this to me last year and then turn around like what are you going to do about it? In a rare move (that I would not have done if he had not deliberately run in front of me and then turned around and gave me a look) I just kept barreling upward, more or less pushing him out of the way- his father grabbed him and pulled him over, saying something to him (parents still chastise their kids for doing this kind of thing, the last vestiges of parental authority).
Yup, petty AF, don't care. In my day, an adult would have just yelled at us to get out of the way, that was back when any adult could call out any kid. Or, worse, if they knew your parents, report you back to them. I got in trouble for not saying hello to someone (she told my mother) when, honestly, I don't even remember seeing her anywhere. So, yes, you kind of behaved better since you would otherwise get called out or in trouble.