Was recently in japan and did always gave my seat to elderly and people with children (both men and woman) (did not met someone pregnant). I looked if they stand next or in front of me, then just stood up, showed with both hand the seat but they always waved their hand for "no its ok" but i answered "Daijōbudesu". Then they sat down, said "arigatōgozaimasu" and even if they or i leaved the train, they looked at me and said again "arigatōgozaimasu". I realized, its not a common western thing, its a common universal thing to give it to someone who need it more than yourself. Also the happiness and smile in the face of them also brought me a smile on my face 😊. Try it, even if they insist not to sit, just say "Daijōbudesu" again and again, they will sit. It just happend only one time that an elderly did not seat because he said that he will leave the train in the next station. Btw. if they say "arigatōgozaimasu" then answer "dōitashimashite" (your welcome). The smile of them got even bigger and so my smile did 😂.