The US has a long history of tax credits and deductions that people finagle to pay as close to their actual tax obligation as possible. (ie. if you do not do this, then you are quite literally paying more than your actual obligation according to the tax code).

The government isn't aware of your donations or losses, or whatever. So you have to tell them about it. Tax preparation software, historically, was designed to make this process easier by prompting you for all sorts of details you may have forgotten or were un-aware of. In essence, the software was supposed to replace a paid tax professional.

Today, most people use Standard Deduction since it was raised so high by the Trump Administration, and the need for credits and deductions has been greatly diminished. However, the need is still there for many folks, and not all tax filings are simple.

The nirvana for tax filing would be a single page online that disputes any facts the IRS already knows (such as informing them about donations or the like). But, our tax code itself needs to be vastly reformed and simplified before that can become a reality.