can't seem to find an answer to what i thought was
an easy question:

earnings distributions from a roth ira, assuming you're
59.5, are entirely tax-free in the USA. but what about
if you're a legal resident overseas, for example, in Australia ?
Will Australia tax these earnings just like they would
the earnings distributions from a regular IRA ?

I did some checking.
It appears that only the US has the authority to tax any US earned income, including that from IRAs and retirement plans.
.