I'm not at all familiar with tax policy regarding inheritance, but is it possible to somehow 'hide' some of your assets in interest bearing offshore accounts in a way that the government can't account for them? I assume that if such a thing were possible someone could save money there and have a beneficiary that could access the account in the event of a death.
The Dynasty families (Gates, Rockefeller, Kennedy, et al.)have all sorts of ways to "hide" their money from death taxes.....i.e. Foundations, where they they hire their family and friends to do work that furthers THEIR interests, and those are not necessarily, the interests of this nation.