They handle school buses which have a similar mechanism, so I would hope it's already a solved problem.

No it's quite dissimilar. Streetcars in Toronto travel in mixed traffic in the middle lanes and deposit passengers into the right lane of traffic, which is expected to stop behind the open doors. What happens if the right lane is occupied by stopped traffic? You have to sit and wait while the passengers do their thing around the hopefully-attentive driver of the stopped vehicle.

Being in mixed traffic, streetcars are easily blocked by disabled vehicles or straight-up idiots. The time between launch and one of these things sperging out and blocking streetcars will be measured in minutes.