Here is a video of how to re-create one of the experimental tags for life again! I do not know how tires are recycled but I do not think they will be safe.
The process of retreading tires is done often on commercial truck tires to save money. It's not so popular on passenger tires because of the fear of the tread separating from the tire body. There used to be a company that sold retread mud terrain tires but they weren't very popular.
Yeah, for the small saving, the lower reliability is not attractive to many people.
Also when they separate on a tractor-trailer it’s not a big deal, but when they let go on a car they can cause a lot of damage and catastrophic loss of control.