Because of capital gains taxes.  That’s why I asked whether GoldCard holders should have to pay capital gains taxes on US source gains (US stocks) when resident in the US.  If yes, then it’s important to understand gold card needs to be a separate category of US resident. 

Most non-resident Americans want to be treated as NRAs, meaning exempt from capital gains.  Not because they’re “avoiding tax” but because they’re often subject to conflicting capital gains taxes in their country of residence.

The point is this: gold card is useful to RBT advocates because it opens the discussion of amending the relevant provision of the code.  But it isn’t what some people have suggested, which is a category citizens abroad can fall into, too.