This question already has an answer here:
I'm a U.S. citizen, about to go from Boston to London. I thought ESTA was for non-citizens entering USA. But the airline shows me a web page saying I must have it to go to or from USA or UK. And not a word to suggest that it doesn't apply to all nationalities.
The application form suggests that my first thought was correct and that I don't need it. Since my first leg to BOS boards forty hours from now, this is a disturbing development.
Am I right (not needed) or are they right (I'm in trouble)?
UPDATE: Since I posted the question, they roamed the word "from" and it now says "Visa Waiver Program When travelling to the USA,United Kingdom, all passengers eligible to travel under the Visa Waiver Program must apply for an Electronic System Travel Authorisation (ESTA). Read more"
Clicking on "read more" says a lot about both USA and UK.