Did the parent comment about the Netherlands also apply to business owners? I have dealt with business taxes in other countries besides the US (though not Netherlands) and you absolutely are expected to hire an accountant to do it. It may well be impossible to file them otherwise. In the US for the most common businesses you can do pass-through taxation and just add a schedule to your regular return.

Even in a pass-through business that can use schedule C or E, this part is still almost always false: “IRS already knows what how much tax an [individual] owes”. They almost never have enough information to correctly and completely fill out schedule C or E for you.

Sure but the point was the comparison to the Dutch system, hence the "...like the Dutch government" part of that sentence. So while its great to make sure people are clear about describing tax laws here on the internets, it may not be an aspect of the argument that is relevant.

I read that sentence most plainly as having two claims: The IRS has enough information to prepare returns for US individuals. This is similar to the Dutch ability claimed above.

Rather than as “the IRS has the same limitations in individual tax return preparation as the Dutch system”.

(GP then goes on to claim that while the IRS has this ability, they are philosophically opposed to this becoming the standard method of tax preparation, which further biases me to thinking that the first reading was their intent.)