Toronto is cracking down on one of the most visible and infuriating of its urban blights: Drivers who “block the box,” entering intersections they have no hope of clearing before the light changes, obstructing vehicles — including buses and streetcars packed with commuters — trying to proceed in the crossways direction. Then drivers going the other way do it. Over and over and over again, every rush hour. If Toronto traffic were your friend, you would organize an urgent intervention.