I ride public transit on a daily basis. Some standing adult passengers do not hold onto a vertical or parallel bar to avoid falling when the vehicle is in motion. Instead, these passengers spread their legs apart to balance themselves while the vehicle is in motion, grabbing a bar to avoid falling only if the vehicle is moving at high speed or suddenly stops.
(My classmates and I as teenagers would do the same thing while riding on public transit vehicles---spreading our legs apart to balance ourselves while the public transit vehicle is in motion.)
