We know why the IRS disproportionately audits low income people, because the IRS Commissioner said so. It’s a result of intentional budget cutting on enforcement. They don’t enough investigators, so they go with the easiest to audit, people making less than $20,000.
Your own source links to an article which says that people whose incomes are over $1 million are much more likely to be audited than EITC recipients. $500k to $1 million is when your taxes start to really get complicated.
Honestly, if that's where the cheating takes place, they should go for it. It is disingenuous to say that they get audited more than the wealthy, though. Because they don't.
It's not just the population size. Those receiving the EITC are audited at a much higher rate than any other group making less than seven figures. You are correct that the rate goes up after that.
This is a policy decision from top to bottom.
https://www.propublica.org/article/irs-sorry-but-its-just-ea...