The US would never allow other countries to follow the US’s own rules.
Consider the US’s (successful) attempts to strong-arm foreign banks into honoring US FACTA banking laws. If they have any dealings in the US - and most do - they must report all banking information on “US persons” to the IRS or face massive fines.
“US persons” includes many people who don’t hold a US passport. Not just former Americans, but their spouses and children who have never considered themselves US citizens or been to the US. Needless to say, many consider it a privacy violation by a foreign country. Canada eventually signed an agreement with the U.S. and passed its provisions into law allowing and forcing banks to comply.
Think of the implications of mirroring that.
Ted Cruz, despite giving up his Canadian citizenship, will still be a “Canadian Person” under banking laws. All his banking information - even if he becomes President - must be reported to the Canada Revenue Agency. Canada could investigate him for off-shore companies, etc. And that means that a foreign government could pressure a US President in ways Americans might not like.
The same goes for others in Congress. There are eighteen foreign-born members of Congress, and likely many more with foreign-born parents and spouses. Imagine the hissy-fits when their banking information is automatically sent to Germany, France, India and elsewhere.
The same goes for millions of Americans. And millions of foreigners residing in the US because the US taxes them at a lower rate.
It ain’t happening.
