Part of the trouble with "realistic" films is that, really, you have to editorialise. Living in London for a year I took a look at some shitty flats, there were tons of grey depressing days and there were plenty of dirty overcrowded high streets, bus stops and tube stations. My job was boring, I didn't earn a lot of money (and I spent even less) and I didn't socialise much. I could edit together a two hour long film from my memory with me as the quiet (deep, attractive, talented) protagonist that could make a "deep" meditation of the indignities of modern, materialist London that was all true. But it would be extremely dishonest for me to do it; I loved London.
A possible response is to say that I don't really know what it's like to grow up in a flat on Wood Green High Street and I come from an upper-middle class background so my perspective doesn't capture anything, context is everything! And that's true, but if we go this route, how exactly are we supposed to judge a gritty urban drama's realism other than an intuitive sense of something ringing true and maybe a few bonus points for general depression? We don't have the tools to interpret mannerisms, unspoken rules etc of the community being portrayed, so either it's really true to life and we don't understand a fucking thing, or the artists has to "train us" to see it in the way we're meant to, which I can't help but feel involves a lot of deviations from the way things actually are out there.
The movie Half Nelson went for gritty realism, but I'm deeply sceptical of its value. A better try comes from The Wire, it leaves out the deep inscrutable looks of characters as they ponder their existential angst in favour of dumping the viewer into the middle of its world and leaving us to find our way around, and they can get away with it because they have hours and hours to do it.