Both Capitol and you seem to think it is a bad thing to get a cold and challenge the immune system. Britain has the highest rate of childhood asthma in the world! We need to stop using crap like antibacterial washing up liquid and eat a peck of dirt a day. (Actually, a peck might be a bit too much, but you know what I mean.)
Not only does public transport strengthen your immune system for later life when, faced with things like cancer or other horrid diseases, we're all going to need a healthy immune system, but also you get to mix with other members of society and have to adapt to their funny little ways, just as they adapt to yours. This is another healthy aspect which Britain is missing more and more. And we all know what huge problems we have in Britain trying to establish a cohesive society, when that daft old bat Thatcher tried to pretend there was no such thing.
Moreover, on public transport, especially trains, you can read a book or the newspaper (and get up to date on current affairs), you can do some work, perhaps write a novel. Cooped up in private cars we are continually faced with danger, it is unhealthy, antisocial, dangerous to kids and the elderly and costs the NHS millions to patch up all the injuries cars cause. Sure, lorries also cause accidents, but most lorry drivers have had to have extra training to drive their lorries and are more responsible drivers by and large (excluding white van man, of course - they should all be dragged to the side of the road and bludgeoned to death with a pickaxe).
MM