Quite frankly, even though I don't ride public transportation anymore, I would love to see that for the future!
When I had to use Chicago's modes of transportation years ago, I would've preferred to sit alone sometimes. There were some men that were so heavy and plain ignorant in the way they sat or there was the person that fell asleep and started to snore...a number of reasons come to mind.
In this day and age especially, if I were a young girl, I'd be more afraid if some creep sat next to me! To say no to someone if they asked, could also be a problem as well.