The Chevy Volt has the perfect handling of this: A new car never charges past 90% or drains below 10% battery. It simply reports 100% when the actual battery isn't quite full and vice versa, extending the battery life significantly.
As the battery life degrades over time, it will try to keep the same useful range, and shrink those boundaries until you are using the full battery life each charge.
Perhaps this works less will for phones, but I'm not so sure. Personally I never have issues with battery on new phones. It's only as the battery life shrinks that you really need the full range.
I've never understood why these companies don't just add a redline: make the battery chargeable to 110%.
By default have it stop charging at the recommended 100%, but let the user decide if they need that to go beyond that and are willing to damage their battery health to do so.
Most users don't know enough about battery chemistry.
WAY too many people don't even understand how USB charging work, their brains are still stuck in the barrel jack charging ages where the charger pushed power and the device just took it (or blew up).
As the battery life degrades over time, it will try to keep the same useful range, and shrink those boundaries until you are using the full battery life each charge.
Perhaps this works less will for phones, but I'm not so sure. Personally I never have issues with battery on new phones. It's only as the battery life shrinks that you really need the full range.