P.S - Do you think a country like India, can genuinely monitor every cryptocurrency transaction?
Yes, it can if it is done through a KYC verified Indian exchange
This wouldn't be enough. We have stock market which is fully transparent. But still government is unable to automate the regulatory requirements on the trading of securities. They failed to bring the trading of securities within the purview of GST. In income tax as well, the responsibility to report trading profits is on the tax-payer.
Comparing to the stock trading, the trading of cryptocurrencies is even more complex. Along with the problem of recurring transactions (same unit of security being traded again and again), there are too many leakages and injections in this market. You can literally buy cryptocurrencies over-the-counter and no one even notice that the ownership of the coins have been shifted. Then you can easily sell the same coins on KYCed Exchange and claim the sale as anything (capital gain, income from business, return on investment, anything). It is too complex to trail back the source of coin and locate the real source of income.
It is almost impossible for government to monitor the entire market. Yes, they can ask for the transaction records of certain traders, issue them the notice. But in the end, government still have to rely on traders to report the source and profit element in their transactions and they don't have many means to verify its authenticity.