Also, how can the government track our transactions?
In most countries tax is taken on trust. You declare it, calculate it and pay it. No one has the time or interest to track everything. If they believe there's an anomaly then they'll start to properly investigate things.
It's automatically checked with data they also have during the year
It's quite easy. They just wait for citizens to report wrongly and then start to get manually after you (sending you a letter, etc) In my country, the Taxes authorities hired developers and now use Big Data with algorithms.All agents say it's so awesome.
and it will be pretty easy to include crypto in.On top of that now taxes are paid every month, deduced from your salary, making it harder to cheat.