What you need to do is address how people feel, and transit advocates have been doing a poor job at that in the US.
People feel safe in their cars. People feel unsafe on transit. I don't know why this perception deviates from reality, but it does. Maybe it's because in a car you have tons of steel surrounding you from the drunk driver, while in transit you have at best your clothes protecting you from the psycho.
Address this, and you will win over many people to transit. But again - I feel like most transit advocates are highly resistant to doing what needs to be done.
I have nothing against well run transit. I love taking the subways in Seoul, Tokyo, Hong Kong, and other cities where subways are ultraclean and nearly devoid of potentially dangerous individuals. I hate taking the NYC subways because almost every other day I encounter someone I feel wary being in the same car or station with.
You're simply not going to win over hearts and minds by stating the homeless guy in the subway car raving about some lunacy is completely harmless and you should just ignore him and let him be. Even if he is actually harmless beyond just stinking up the air and causing a nuisance.