Why people don't give up their seat on train?

Unfortunately these days (especially in Singapore), it’s like that. When I was pregnant till after I give birth and had to take public transport with baby in carrier, it’s always the elderly who gave up their seats and insisted that I sit. Sometimes I felt bad cause I feel that they needed the seat more than me but they will insist, yet youngsters seating right beside (priority seats) don’t offer. But then again, we may never know if anyone is ill or maybe they needed the seat to rest and…. they did paid the fare so they are entitled to the seats.. I never dared to ask for a seat while pregnant cause I scared people scold me 😅. However I’m thankful and grateful to those elderly that offered me seats thru out my preggo journey. IMO, if you really feel unwell and need a seat, just ask nicely 😊.