I mean I haven't seen a serious article claiming full protection, usually something like 60% against catching delta, and a bit higher against serious complications. The vaccine helps you but it doesn't make you immune.
What it does is greatly reduce the speed of transmission - 60% reduction...
Unless those guys all blow up their teslas.
The other issue is that it's a matter of rate of growth; as long as Tesla is producing more and more cars, there might be more cars that need replacement batteries than there are cars that can donate old batteries.
You can use Chaos or just do it the way we used to - with a trigger.
Create a new hero, adjust the xp, give him the items, remove the old hero.
You can make your hero sell a unit that serves as the button for upgrading.
Just keep in mind that there aren't a lot of slots for buttons on the hero.
Throwing away the fire alarm because it's ringing all the time isn't the real solution.
The real solution is to have "free" tutors, but that costs lots of tax $.
This kind of personal assessment based grading & guidance can work (it's how companies have done business since a long time) but...