There's reasons for charging $10 per domain other than the cost of the DB line
One thing I can think of off the top of my head is that it makes domain squatting a bit more expensive. $10 instead of 2c is 500 times less domains for the same amount of money. At the same time, $10/year is a reasonable entry price for "I'm seriously considering using this domain"
Domain names are a scarce resource, it makes sense to charge a good amount of money for them
On that basis, I and I alone should have the monopoly and should give as much to icann as I deem appropriate. It's as good as the current system for your argument.
If you want to make the argument of the necessity of a tax who gets it? Those who were on it early enough to capture the regulator. Interestingly on a philosophical level both republicans and democrats claim to hate regulatory capture.
Republicans would want to open ICANN and it's intermediaries up for competition, democrats would prefer to nationalise the lot, yes I know, that's just the ideology not the behaviour of elected official much of late.
One thing I can think of off the top of my head is that it makes domain squatting a bit more expensive. $10 instead of 2c is 500 times less domains for the same amount of money. At the same time, $10/year is a reasonable entry price for "I'm seriously considering using this domain"
Domain names are a scarce resource, it makes sense to charge a good amount of money for them