You tax the non reproducible assets like money [0] and land.

The reason is quite obvious. You can't make more land so you have to force owners to use it efficiently. Money is transactional real estate, it grants the ability to perform transactions. What people call "saving" is actually just holding onto money and blocking the capacity, it's no different than blocking a lane on the high way and building a toll booth on that lane. Money is strictly a pass-through asset. Certificate of Deposits are fine because they are contractual agreements with finite duration, liquid money has infinite duration so its corresponding debt is also of infinite duration so that needs to be taxed.

[0] No, infinitely expanding the money supply is not a solution, because it also means infinitely expanding debt.