Currently, governments can only tax cryptocurrency exchanges and users in those trading networks. Apart from the exchanges they manage, there's no other way to collect taxes. If they want to collect taxes on Crypto users, they need more specific and complete rules
Exactly. As long you keep trading crypto on centralized exchanges, you'll be subject to paying taxes on your crypto funds. There's virtually no way governments will be able to enforce crypto taxation on decentralized exchanges and P2P marketplaces. The situation becomes even worse with atomic swaps as the exchange from one coin to another happens between chains without the need for a middleman whatsoever. Once governments see they're unable to tax crypto in their entirety, they'll most probably ban the whole ecosystem as we know it. If this becomes a reality, then people won't be able to use cryptocurrencies as they normally would, greatly diminishing the value of the entire crypto market. One way or another, crypto needs the governments' approval to succeed within the mainstream world.
The other choice governments have to make people pay their crypto taxes, is to implement strict regulations to the entire Blockchain industry. Perhaps, they won't allow developers to continue working on decentralized solutions such as non-custodial mixers, decentralized exchanges, other privacy tech, and even P2P trading software. If they manage to do this, then crypto will be entirely subject to centralized exchanges as it'll be the only way people will get access to them. We'll see how everything unfolds within the future as governments start rolling in their own digital currencies for the world. As governments want to maintain supremacy, they don't want alternative payment systems taking over the existent financial infrastructure. They have already rejected Facebook's Libra stablecoin, and they can do so with crypto until Fiat is the only form of payment used within the mainstream world (as it was before crypto's inception back in 2009). Let's hope that everything turns out great in the end for the growth of the crypto industry in general. Just my opinion