Why we never developed a vacant land/land value tax on parked domain names has always been a mystery to me — speculation through domain name squatting (and, to a more extreme degree, cyber-squatting) has always left a bad taste in my mouth.
The early internet was pretty non-commercial, and a lot of valuable domain names were taken by projects that do something useful or cute, but cannot generate any serious money, or any at all. An introduction of an LVT equivalent would unsettle all these small projects.
Another question is how to compute the value. I see only one non-arbitrary approach: to auction off every domain every year; the sum paid would be the tax. Cybersquatters would win many such auctions, but of course only for domains they think will be in demand soon.
Another question why dmv.org should in any way be related to DMV; I'd expect it to be DMV.gov because it's a governmental agency. You can't squat a .gov domain.