A quick look suggests 'they' have made some attempts to persuade people that they can identify appliances by the back EMF, but, if people think they're going to charge me extra on that sort of evidence, they can piss right off. You could, perhaps, identify usage to some rather vague extent, but this would require calibrating each appliance in the house, and every new item introduced, and being honest, unless 'they' come round and do it for you, which seems unlikely and self-defeating.
The only real way, as you say, is a dedicated supply from the meter and people could still slow-charge, avoiding that. There is no way of dyeing the electricity, like red diesel.
You could make chargers, or cars, such they would identify themselves to the meter, but that seems unlikely at this stage in the proceedings.