In my very limited, layperson understanding, all of these fancy multi-country tax schemes involve separate corporate entities in each country which then engage in some set of fictitious transactions (e.g. IP licensing fees) to move money between countries.

Also in my pedestrian understanding, around taxes on the value of some hard-to-valuate asset, one mechanism for encouraging owners to be honest in their valuations, rather than under-valuing everything, is that some party (perhaps the government) should have the option to purchase some property at the value claimed by the owner. "You say this trove of old master artwork is only worth $100k? I'll take it!"

Is there a reasonable form of this for the colluding branches of multi-nationals? "You've claimed your subsidiary in our country has had $0 net revenue every year for the past 10 years b/c it spends absolutely every available dollar on IP owned by the sister company across the pond? Then since we agree your subsidiary is really clearly struggling, I will buy it for the value of its local real-estate portfolio, plus a small markup."

Tax money leaving the country and have a foreign entity tax.

Apple has closer to $93b[1] on hand vs. $1t quoted.

[1] https://finance.yahoo.com/quote/AAPL/balance-sheet/