Domain names have property value, despite what some of the special interest lawyers would have you believe. That can readily be seen since they have monetary value, and are often auctioned off by squatter organizations. Domain names do not belong to the registrars, despite what some of THEM would have you believe. They are invented by the registrees and not the registrars, and the registrar function is to make sure they aren't already taken, and to provide address and routing space for them. They are likely analogous to a copyright or trademark, though perhaps not in the strict legal sense.
Domain names expire regularly due to non-payment, etc.
Some unscrupulous registrars have been seizing those names thought to have value, and then trying to sell them. It belongs to the general public, just as does an radio frequency whose license has expired. But it is a very complex matter to establish, much less remit such value to the general public. Full-information auctions are a reasonable way to establish the value of an item. That an expired domain name be placed on a 30-day hold to allow the original holder to recoup it on full payment of any fees due. 2.