Check out this San Francisco Chronicle article on anti-abortion ads on BART enraging passengers.
I don't find any political/social banners on BART offensive, and even if one day, there is a political ad with a message that is totally against my personal beliefs, I would just ignore it and not express my disagreement, not to BART, and not by defacing the ads. Americans forget how fortunate we are to live in a country where speech and expression are protected under law. Why shouldn't pro-lifers and religious groups have the right to communicate their message? Why should BART get reprimanded for allowing these ads? Why can't pro-choice activists contain their emotions and bring their debate to an appropriate forum instead of tearing off these ads like unreasonable children?
Taking an objective stance on this, I thought the outrage was unnecessary. We are all entitled to our own beliefs and opinions, so why not let others exercise their right to speak and express?
More practically, BART advertising revenues probably in some way have slowed additional fee hikes. So why not just allow all point of views the right to communicate their message?