[ttoinou]

You need to take into account all the simplification it would imply in tax collection / paperwork / regulations etc. The cost of our current ways of taxing wealth and profits is huge

[JimmyAustin]

In the US, the IRS collected $3.33 trillion in revenue in 2018, with a total budget of 11.5 billion (2017). Thats 0.3453%, or 35c per $100 of tax revenue. Fairly minor in the scheme of things.

[ttoinou]

Monetary costs are a small subset of general costs (and the cheapest ones, easier to know and aggregate).

[jpadkins]

that's only one side of the ledger (collection). Now calculate the costs to the taxpayers (people and corps).