- Most people with a kid
- Most people supporting a relative
- Most people supporting someone who has no income and lives with them
- Most people who made charitable contributions in 2021
- Many people with a home energy deduction
- Most people who participated in post-secondary education
- Anyone in the gig economy
That's a big list, and it's far from complete. So it's not clear that your proposed "do people's taxes, leave it up to them whether to acquiesce or not" plan is good for consumers overall.
"This isn't hard" -- as illustrated by both my and your mistake, this is as far from the truth as could be. Everything related to taxes is absurdly hard, whether it's setting up the right tax prep system, the right level of complexity in the tax law, or simply the right return to file as a taxpayer. My overarching point here is that Congress made a certain value judgment as to one of these very hard problems—that a healthy industry dedicated to getting people's tax returns correct might be in the best interests of both the government and taxpayers—and this might not actually be the product of corruption.