The rich have more assets and income sources and have staff who do a bunch of financial chicanery to try to hide their tax evasion. Auditing the rich requires significantly more work than the poor.
These decisions are not about doing what makes sense. The IRS is a revenue generator. Spending money on the IRS brings in significantly more money in unpaid taxes than it costs.
The goal is not to do what's best for the government's budget. Its really about ensuring that their criminal friends can continue to get away with it.
This is a transcript of a meeting. Those are words that trump did say, but this screenshot is cropped deliberately to hide that fact.
This is one of the typical lies that trump is known to make in speeches. This isn't a whitehouse staff member publishing those words as a written statement the office stands behind.