Here in the US, they don't. https://www.propublica.org/article/irs-sorry-but-its-just-ea...
"Congress asked the IRS to report on why it audits the poor more than the affluent. Its response is that it doesn’t have enough money and people to audit the wealthy properly. So it’s not going to."
They bumped down financial institution income reporting down to $600. Going after low earners instead of going after the affluent.
Here in the US, they don't. https://www.propublica.org/article/irs-sorry-but-its-just-ea...
"Congress asked the IRS to report on why it audits the poor more than the affluent. Its response is that it doesn’t have enough money and people to audit the wealthy properly. So it’s not going to."