Everyone can use as much power as they have subscribed to whenever they want. Your panel is rated for a certain amount of power and protected by a breaker or fuse if too much is used. Same for the transformer your panel is connected to. Same for the distribution line your transformer is connected to. Same for the transformer it is connected to. And so on.
There is enough capacity in the system to meet the demand. If there wasn't the lights go out due to some overload.
When demand grows more capacity has to be added before the limit is reached. Capacity takes years to build. Utilities have planning departments that decide where they need to add capacity next and how much.
The expectation is that people drive 30ish miles a day. This is about 11kwh. Over 8 hours a night, well within reasonable limits.
Lots of plugged EV’s are also the perfect pairing to rooftop solar — in Hawaii, they’ve had to stop people from installing panels on their homes because the neighborhood feeder circuits can’t handle the power being generated by all of the homes. Just redirect that power to the EV in the driveway (or your neighbor’s driveway), problem solved!
A house with a 200A service at 240 V is about 50 kW. You might see a 250 kVA padmount transformer feeding half a dozen big houses but that is not the same thing as a substation.
5KVA per residential lot is not an uncommon allocation rule. The network is simply not designed to supply every house 200A simultaneously (the same is true of water services: the maximum flow rate of your connection to the water main cannot be sustained if every house in your neighbourhood tries to consume at that rate).
Granted you can probably overload a transformer a fair bit on a cold night. I'll ask next time I'm talking to someone in distribution what their allocation rule is.
I feel like I'm used to seeing a 3 x 33 kVA cans feeding only a few houses (that incidentally had natural gas heat and hot water...)
