You see a similar story with ecommerce. A business enables bitcoin. No-one uses it, but it's a hassle to maintain the wallets or maintain the upgrades demanded by the payment processors. And when the costs exceed the benefits, it gets removed.
Somebody wanted to buy an electric car, but there were no charging stations so he didn't.
Some other guy wanted to start a charging station business, ....but there were no electric cars.

People don't change their payment habits unless the older ones become more expensive and the new ones are cheaper and easier.
So, why would the people use bitcoin to pay their taxes, especially since you're nor really directly using bitcoin but a 3rd party that, charges also a fee?
Nope, no reason, that's why you have only 10 people paying.
It's more convenable via a card or a wire, does it imply less hassle than counting satoshis and live afterward with the fear that you've just left a track to your stash or your other spending habits?
Am I surprised? I would have been surprised if it would have been a thousand!