'especially given law changes and thousands of options that exist'
The IRS needs to have this logic and data import anyway to be able to verify the return. So, all they really need to do is process everything by say March 15, and allow someone to see the data on a website and click (Accept).
I don't think IRS has all the data in one place. E.g. do they have my local property taxes? Do they have record of mileage that I could deduct for charity purposes? Do they have a value of goods I donated to charity? Hypothetical examples, there can be a lot more options, many of them not so easy for them to verify. That's why they audit - then if I am audited, I'd have to prove them it's true.
The IRS needs to have this logic and data import anyway to be able to verify the return. So, all they really need to do is process everything by say March 15, and allow someone to see the data on a website and click (Accept).