You've got any source on this? or just hearsay?
Mine disagrees with you.
https://www.usa.gov/become-us-citizen
Five or six years ago, when I first looked up this information most U.S. Government references listed the following:
"Title 8 U.S. Code § 1481 - Loss of nationality by native-born or naturalized citizen; voluntary action; burden of proof; presumptions
(a) A person who is a national of the United States whether by birth or naturalization, shall lose his nationality by voluntarily performing any of the following acts—
(1) obtaining naturalization in a foreign state upon his own application or upon an application filed by a duly authorized agent, after having attained the age of eighteen years;"
Followed by a statement that the U.S. assumed the Citizen did not want to lose citizenship and therefore citizenship was not revoked.
It is logical from the information presented at the time to conclude tax revenue was the motive behind this as the U.S. charges taxes to citizens, even if they live in another country and that money was earned in a country outside the U.S.
Which is were my statement of technically illegal came from.
Since then U.S. Government sources have added "with the intention of relinquishing United States nationality" to Section (a) of Title 8 U.S. Code § 1481. However, some sources still have not added it, while others indicate "as amended".
Keep in mind for naturalized citizens, renouncing your previous citizenship is part of the oath of allegiance taken when they become a citizen.
“I hereby declare, on oath, that I absolutely and entirely renounce and abjure all
allegiance and fidelity to any foreign prince, potentate, state, or sovereignty, of whom
or which I have heretofore been a subject or citizen;"
Which can lead to loss of citizenship due to concealment of material fact or willful misrepresentation, if the U.S. chose to enforce it.
My apologies for not updating my research six years later before making a comment on a forum.
However, current sources still indicate that you must formally renounce your U.S. Citizenship and pay a non-refundable fee of $2,350 in order to avoid U.S. taxes.
References
Losing or Renouncing U.S. Citizenship
U.S. Taxes
U.S. Oath of Allegiance
