The way I see it, being an urban sketcher isn't merely about drawing cities, big or small, urban or rural, with a pen or with your fingers on an digital tablet. It's about drawing places that can be put on a map, and everything that happens in those places. It's about showing the world with drawings, taking people to locations they may never go through artwork only you can create. You were there, you saw it, you sketched it, you told us what happened with your hand drawn art, sketched in the moment but perhaps touched up later because you ran out of time or can't resist the urge to fix something up. What matters is that you "draw what you witness," as my fellow sketchers in Indonesia like to say.
Those beautiful vases of flowers or the bowls of fruit on your kitchen table are sure great subjects to draw, but do they tell me something about a place I can put on a map? There are countless of beautiful sketching subjects to be drawn from observation that don't quite fit the spirit of urban sketching: an out-of-context portrait of my friend or her cat or her baby or her baby's shoes, for example.
But there's no point in making lists to define what urban sketching is or is not. You know what it is already, you've probably been an urban sketcher for a long time!