"The grid can't handle it" is a bullshit argument that is easy to sell to people who want to keep their IC cars. The difference between highest demand and lowest demand in Ontario this week was 7000MW, if everyone charges their car at night there is power available AND it helps increase the base load which is good for the gird operators.
Even individual buildings may not need to upgrade their main service even with rapid chargers, the operators just need to keep in mind not to run the oven, dryer, AC and car charger at the same time.