Not every charge/discharge wears on the battery the same. Staying at 0% or 100% is worse than staying around the middle. Charging and discharging extremely quickly wears more than slow charges/discharges. And high temperatures are bad for battery health in general.

Electric car batteries are tuned much more conservatively than phone batteries and are massively over-provisioned because US consumers are nervous about exactly the thing you're talking about. That's not too surprising because to a large degree the car IS the battery, but battery wear is generally very well mitigated (with the exception of the Nissan Leaf).