PPP was part of the cares act.
Sure you and your customers weren't committing fraud. But, there are millions of people out there just waiting for fraud opportunities. It's what they do. Those people sat on the sidelines while the gov't offered $700 billion, and was rushing to get it out?
You've mentioned "tax forms" as reasons people can't cheat. All someone had to do was fake a 941, fake a payroll report, fake a whole tax return if needed. AFAIK, banks weren't required to 4506 to make sure they were holding legit tax returns.
The IRS still hasn't processed millions of tax returns for 2020. Millions of people due stimulus checks are still waiting because the IRS can't (or won't) catch up. The phone answer rate at the IRS is ~30%. It's not like they have a legion of people sitting in a building somewhere verifying loan documents vs. 941s. The SBA has 3,000 employees, most of which already have jobs and responsibilities. Other than the large (>$2 million) loans they said they would audit, do they have personnel to do any in-depth looks at the millions of loans that were less than that? Probably a very small %, if we're being realistic. The fraud was probably massive, and we'll probably never know the extent of it.