Just as the progressive income tax is apportioned by class.

Just as a gas tax is paid only by those who only use gasoline and a tax on carriages is only paid by those with carriages.

https://www.americanbar.org/groups/taxation/publications/abataxtimes_home/19aug/19aug-pp-johnson-a-wealth-tax-is-constitutional/

The Constitution, Article I, section 9, clause 4, requires that a “direct tax” must be apportioned among the states by population.3 For the Founders, a necessary element to be a direct tax is that apportionment among the states by population must be reasonable and just. Thus import taxes (the impost), excise taxes, duties, carriage taxes and now real estate and wealth taxes have been expelled from the definition of direct tax, sometimes by the operation of ordinary language and sometimes by Supreme Court decision.

snip

Hamilton put it quite clearly.

A constitution cannot set bounds to a nation’s wants; it ought not, therefore, to set bounds to its resources. Unexpected invasions, long and ruinous wars, may demand all the possible abilities of the country. Shall not your government have power to call these abilities into action? The contingencies of society are not reducible to calculations. They cannot be fixed or bounded, even in imagination.7