You need to do some travelin'! Your perception of mentally questionable people taking public transportation may well apply in the USA, but in other countries it's simply not the case.

In big Russian cities it is way more convenient, cheaper, quick, and as pointed out -- mentally relaxing -- to take a tram or subway than to drive your car in the insane traffic. The clientele on said public transport are, for the most part, friendly, and you will see men scrambling to help old ladies or women with strollers onboard.