Why is a tax on consumable goods the most equitable, or fair, form of taxation?

A tax on consumable goods treats people indiscriminately, and does not take into account prejudices against the certain classes of people, which inevitably leads to strife between classes. Likewise, citizens can choose the amount of taxes they pay, by choosing whether or not to buy those consumable goods. Finally, those who purchase more consumable goods because they have more financial resources, will pay more taxes, because their taxes are in proportion to their consumption.