Try California.
That sounds like the exception that proves the rule, especially since this particular bypass seems aimed to specifically enable lawmakers to elude the laws they bestow on everyone else.
This is a very useful example for several reasons. First, it's not anonymous, it's pseudonymous. The DMV knows exactly who these plates are issued to, they're just not telling. Second, it reminds us that if the proxy that knows who the registrant is doesn't cooperate, they might as well be anonymous. And third, even though these registrants are carefully vetted upstanding members of society, they're still routinely abused. Anonymity encourages anti-social behavior. I can't imagine why anyone would think this was an argument in favor of anonymous vanity domains. R's, John