LOL. You say Amps is the wrong word and then you go on to explain, using AMPS! Amps to Watts or vice versa is a fairly straightforward mathematical equation. Like Kilograms to Pounds. Unlike fluid ounces to pounds, one is volume the other is weight, you need more information to do the calculation.
Ever been at an empty gas station and notice how fast it can fill a tank. And then at a totally full gas station and notice it takes longer? Wonder why? It's because each "pump" isn't actually its own pump. It is one giant pump sending gas to many valves, so the volume that can push through slows down the more valves in use. Like running the shower, the sink and the washing machine all at once. The one copper pipe can only send so much water so all devices get less.
I didn't say all were diesel generated. Many are. You are talking about charging a single car vs many cars. You need a lot of AMPS to charge many cars using "rapid charging". Many people don't have those rapid charging adapters. They use what amounts to drip charging in their garages.