Perhaps it could be due to the fact that you are legally required to yield to pedestrians in a crosswalk? Not to say that people do yield often, but once a pedestrian is in a crosswalk, not yielding is a great way to get a quick ticket.
Yes of course that's what it's due to. But those laws are made for people who need/want traffic to stop so they can take their time, which is understandable. But when you're willing to wait three seconds on the curb for the one last car before a large gap, but you have to turn your entire body away and pretend to daydream just so that it won't needlessly stop, sensibilities have gone too far in the other direction.
