Who Takes Priority??

Saw this scene one morning while travelling on the MRT. All seats on train were taken up and a lady who is pregnant was taking the priority seat. As the train stopped at the next station, another preg lady boarded the train... This one is having a larger tummy! My... i can't believe this... The preggy lady on priority seat stood up and offer the seat to this 'more preggy' lady! What were the rest doing?? One seat down, the lady was sleeping. Another seat down, a lady was reading (pretending not to see maybe). Another seat down, an uncle was simply looking and avoided looking, maybe thinking "I'm too far off to offer my seat". Another seat down, another reading commuter! What a world...