You don't care to give your ID for the KYC. Your Taxes department know you already and since it gives all your details to Refundo, what's the problem?. If someone doesn't want to send a document to this company then he shouldn't accept to be refunded in Bitcoin.
When you receive a refund from the Taxes department you usually consider it as your yearly bonus, since the money was already spent months ago. Savers like to use this money to save more. Someone in crypto can choose to save this refund in the hope that it will increase in value.
You pay $1000 per year
You received a refund worth $300 in bitcoin and after some months the price goes back to $20,000.
=> You won't pay any tax the next year ($1,000 saved). You will pay only 50% in 2 years, (500$ saved). Your purchase power increases
Now you say can the price may go down, it's volatile, etc, but someone in cryptos knows it already and takes the risk. Since it was a 'bonus', after all. Not saying it's free money because it isn't, but it's like when you win with a scratch ticket
Now another thing to consider.
You got your refund $300 and the price is now $20k. You sell to USD. Another point where the Taxes Dept will get free money again.
Since you will have to report the sales to be taxed appropriately. It will another airdrop with free money to the govt.