I find that I have plenty of personal space on mass transit as long as there's enough transit. If I'm taking the 2/3 subway (in New York) or the 27-Bryant bus (in SF) at 9 AM on a weekday, it's totally fine. If I'm taking Caltrain southbound at 9 AM on a weekday or the 4/5 towards the Upper West Side at 5:30 PM, it's miserable.
That is to say, there's a known solution already: funding.
That is to say, there's a known solution already: funding.