It's kind of messed up that not only we have to pay tax, but the government doesn't even have the responsibility of telling us how much we owe it or what specif

It's kind of messed up that not only we have to pay tax, but the government doesn't even have the responsibility of telling us how much we owe it or what specific work which it did is covered by the payment. This is wrong. The IRS isn't allowed to tell us how much we owe, because a certain party currently in power has spent several decades preventing it from doing so. The IRS would love to have a system like they do in other countries, because it's way simpler than what we currently have, and for most taxpayers they already have all of the information they need to do it. For the remainder of taxpayers (including especially gig workers and other independent contractors): the IRS doesn't have all the information it would need to calculate income tax correctly; so these taxpayers would have to stick with the current self-calculation system even if the IRS were allowed to switch to the IRS-calculated system. And on that second note: if the IRS disagrees with how much you claim to owe, they tell you how much you owe based on the information they have. It's then the taxpayers' responsibility to correct them by providing additional information. If it comes to an audit, the IRS will tell you in exacting detail exactly how they determined your tax liability, even citing the specific laws and regulations for any items in conflict.