As anybody who lives in a big city knows, there are times when space-commadeering is acceptable, and there are times when it is unacceptable. There are no hard and fast rules, but like porn, you know unacceptability when you see it. For example, in the subway scenario, a shoulder brush is sometimes unavoidable but a crotch-fondle is never warranted. Similarly, a car entering the bike lane to get around a garbage truck or to parallel park might be the equivalent of a shoulder brush. But sitting in an expensive car and having a cellphone conversation in the middle of a bike lane during the evening rush is just a full-on ball grab.