There are a couple layers to this that I think need to be mentioned. The first thing to keep in mind is that when you consider privacy you also need to consider all future technologies as well. While we might have some degree of privacy now, in 5-10 years someone is likely to create an AI that is super effective at finding patterns in peoples spending habbits with a large enough degree of accuracy that all of your past transactions and wallets will be revealed publicly.
The second point is that, while the government will have an easy time keeping tabs on legal businesses this will be extremely hard for them to keep track of the value of digital goods in general. This will probably fire up a huge debate on where to draw the line on what is or is not a valued digital good.
Should CS:GO weapon skins worth thousands of dollars be taxed? How will these kinds of things be tracked? How exactly will we be able to know how much money someone really has and how will we be able to determine who owns what. Mark my words, its a matter of time before some kid gets a super rare sword in an MMORPG and it results in the parents owing an additional sum of money during Tax season.