I've had that problem too. Sometimes I think, there ought to be a rule against standing when there is seating available. But then again - maybe when the only available seat is next to a disreputable-looking male (like yours truly) I can understand why some women may not wish to take the option....Problem is trying to get out sometimes, because people tend to stand in the doorway, even though there are plenty of seat free for them.
Reminds me of the time-honoured rule (is it still in force?) prohibiting standing on the top deck of a double-deck bus. But I think that was because it might invalidate the old tilt test: