You might be confusing combined theoretical peak loads with working demand loads in the real world.

Actual electric cars don't have 100 kWh packs, for starters. Most people are fine with half of that, 50kWh.

Also, very few people go to fast chargers with a 0% battery state. Most people also don't leave the fast charger with 100% battery state. In practice, it's more common to assume most drivers will charge 50% of the battery capacity, which for the sake of argument let's say is 25kWh.

Finally, the actual fast charge rate is proportionate to how close to empty the battery pack is.. a Tesla at 25% SOC topping up to 75% SOC might only start the charge at 100-150kW, tapering down below 50kW.

Yes, a very busy supercharging station in a dense city needs a fair bit of power (and may "peak shave" actual grid demand with on-site battery storage). For most cities however, it's actually not a huge load in practice, and easily implemented (which is why so many cities around the world have already installed them, even cities below 300,000 population like mine).