This 2014 hearing held by the US Senate on Permanent investigations is very interesting.It features Senators Levin and McCain and includes discussion of tax evasion, Swiss banks, tax treaties, FATCA the Offshore Voluntary disclosure programs and more.
The logic of the United States is approximately this:
Homeland Americans use non-US bank accounts.
Americans abroad use non-US bank accounts.
Therefore, (but not acknowledging Americans abroad) both Homelanders and Americans abroad use non-US banks for the same (nefarious) reasons.
On June 25, 2020 Dr. Karen Alpert and I did a series of podcasts where we discussed how renunication will affect your interaction with the US tax system. The key point is that you will still be taxable by the United States on US source income. What does that mean? Under what circumstances could renunication of US citizenhip actually increase your US tax liability?