The cost is minimal and the benefit of not getting hit by a car whose driver didn't realize it was a one-way is pretty high.

Maybe it's an American thing, but I notice people completely flouting driving laws often enough that I don't trust anything but declared intentions when it comes to cars. Crossing at a crosswalk isn't even safe; many drivers seem to think speeding down the street and slamming on the brakes so that the car slides halfway into the designated pedestrian zone is okay.

I've been pretty regularly tempted to climb on top of car hoods on my way across the street without moving left or right.