Different treatment for underpayment penalty and waiver

I see that IRS has recently waived penalty if the at least 80% of the tax has been paid. But interestingly, if this is not the case, TurboTax and form 2210 levy a penalty of 3.6% on the difference between 90% of the tax owed and the prepaid tax. Is this not unfair? Should the penalty not be treated similar to waiver and assessed on the difference of 80% of the tax owed and prepaid taxes? Please help!