at least all financial assets (stocks, etc) are easy to assess value so why not start with that? same with gold, silver etc. Some minimal amount you can make it nontaxable to reduce administrative burden.

this a million times. Land easy, already being taxed. Any regulated financial instrument, also easy, take the minimum average yearly price of held assets. Tricky things like privately held companies, maybe we solve that one later, but even then there are valuations made at various points, anchor to those, be conservative in every case. If the gov primarily exists to enforce property rights... then people should pay in proportion to the rights that are being enforced on their behalf.

The value of stocks fluctuates every second. Sometimes wildly.