In Boston, we cross in front of cars that have a green light :). Although honestly, the cars aren't moving because there's too much traffic to go anywhere as box-blocking laws aren't enforced as it is in NYC.
I'm underlining it was a tourist not because I particularly like Parisians, but because there is enough bike traffic (and little electric cars) that most Parisians know not to cross using hearing only.
I used to be a Bostonian and am a current MA resident, though I work in Cambridge. I've played more chicken on Comm Ave than I care to admit. :)
I'm from NYC and they're definitely not enforced. (Outside of rare exceptions?) They happen all the time. On the major street I live on (two lanes each way), they recently converted one lane each direction to "bus only". There's more cars than fit in one lane, and so there are /regularly/ cars blocking the box, and I've never seen any kind of enforcement, just awful effects to traffic. (Even as a pedestrian. It's hard to predict what the drivers of those cars are going to do, even if you have the signal and you're in the crosswalk.)