[teachingassist]

> But....shares are useless until sold.

This is clearly untrue. At least they have use in the ongoing option to sell. I can use them as collateral to borrow at least as much as, and probably a multiple of, their value.

If you genuinely think they are useless, please give me some. I will use them.

> how can you be taxing someone on a hypothetical sale value?

Since shares are fungible, the government could just apply the tax as a number of shares. Then nobody has to worry about defining a hypothetical value.