But, practically speaking, that's not how people use variable rate charging.

In the vehicle's setup menu, you can choose to "Charge when fees are lower" or "Charge immediately when plugged in" or set a specific timeframe to charge, which is usually late at night. Most people, when charging at home, have a fast charger installed, so even the largest battery is fully charged from fully drained in about 4 hours. And something like 90% of EVs never go below like 40% battery, or some crazy stat like that? (I can't remember the exact number, but it was something like 40-45% battery.)

Then you never ever, in the life of the vehicle, EVER open that menu again. You completely forget that setting ever existed.

In some model vehicles it is possible to adjust that setting via a mobile app ... but I suspect that is rarely used by anyone but the most passionate hypermilers.

Practically speaking, electric cars are just cars you put less gas into. You don't drive them differently. You don't interact with them differently. They are just cars, in the end. And setup menus are opened the first week you have the car, and - if you remember - the last day you have the car (to make sure you delete your personal information and home address before selling it!).