DH and I are 42, our kids are teens, we will all stand to allow elderly or little kids or women with babies to sit. Just makes common sense to me that when the bus is moving and stopping and starting, who will have the most trouble standing...they should have a seat. I am still capable of standing and holding onto the rope thing or a rail...my DDs-17 are completely capable but MIL-70 with 2 bad knees, not so easy for her (as it might also be tough for a little 2 year old or pregnant lady).