The block I'm talking about has "no stopping" signs specifically during school pickup hours to block cars idling. But, either it's a grey area or they just don't enforce - I'd guess the parents would say they are "stuck in traffic" and not just stopped and waiting. Except maybe the one in the front. Either way, if you want to turn left at the traffic lights while that's happening you have to do it illegally from the centre lane to get around them (2-lane roads, but the left is full and the only legal turning lane there).

Closing the streets could work but I think we already have the tools we need (it worked differently in the past, right?) but choose not to use them.