Purely a money gathering exercise. They would tax the air you breath, and the sun that shines on your face if they could.
It’s really designed to prop up and keep the local currency legitimate.
The only reason a local currency has value, is because it is enforced by physical violence. For example if you don’t pay tax in the local currency you can be forcefully imprisoned.
Crypto is a competing currency and money system, it is a threat.
Bartering is also a threat, if we removed money and started exchanging services they couldn’t tax that either. I fix your plumbing, and you fix my website code. Tax that!
There are tax free physical gold coins though - whats the loop hole there?
Do they accept payment in crypto? That would be more manageable. Price volatility can wipe you out, one month you could have a value of $10,000 the next $0.10, and still be in debt for the tax on the previous month.
If they don’t understand how to, or accept payment in crypto, they shouldn’t be taxing it.
The tax system could make someone homeless just because they are farming a coin that suddenly spikes and then drops in value - imagine if your teenage kids computer activity is the reason why you become homeless.
On the bright side, being an investor in maidsafe… and the ONLY coin I own…
I’ve been making consistent losses. 
And very unfortunately 
it looks like the Maidsafecoin asset is going to be removed and will no longer exist on exchanges soon (on launch) - and my crypto keys are going to become useless and values at zero.
The progress on the project, the toys being made and given to us, the bright future more than makes up for the general short term financial pain. 
Tax on homes is another one I hate… some other entity increases the valuation of my home, each year - and on that valuation increases my tax. My house hasn’t increased in size - its no different to when I bought it, yet, by a questionable bank loan industry - prices are inflated. People can’t afford to outright by a house, so the loans make no real difference in the competition between us all. The populations takes the bait, enslaves themselves in more debt than the Jones family down the road so in the end, the bank and the tax man are playing a game - increasing the tax revenue and profits, while the actual physical value and utility of my home stays the same. The game is rigged.
And woe betide you if you have some level of intelligence to escape the game by outsmarting the lazy bankers by investing in a new technology - they will make up a law in thin air, and take that away from you too.
The safenetwork can not come soon enough.
