It might be coincidental but since getting back into picture-taking I've been trying to make sure that fewer films I like the sound of pass me by. I also prefer (where and when possible) to see them in the cinema where they look more like their makers intended and it's far easier to be immersed in the moments as they flicker past.
As Treegonk just said about the station there's something about particular sorts of places (cafés, stations, bus stops, coffee shops et al) which just cry out to be recorded as images, whether it's as a backdrop to a scene in a film or the blink-and-miss-it backdrop to your own life when you walk past the window. Of course, the effect is slightly heightened when you walk past them just after seeing a really nicely-shot film in the same way that after going to a gig I can hardly wait to get home and play guitar and after finishing a book I feel I have to try and write something down whilst the thought of that sort of thing is at the forefront of the mind.
The other side of the people-as-scenery theory is that you're sometimes just the backdrop to someone else's scene too. That's why it's important to act naturally and not look at the camera at all times.