Originally Posted by
ajax
When departing the US, the airline always wants to see my US passport to ensure that I have not overstayed in the US before departing.
That is a very different experience than what I see for my travel parties' members when the US-EU dual-citizens are leaving the U.S. (more frequently on one-way tickets) for the UK and/or Schengen Zone EU/EEA airports.
U.S. airlines check foreign passports for international trips, but the airlines generally do not check these for purposes of the airline determining what is an overstaying or not.
The US -- like the UK -- still manages to have mis-matched (or not matched) arrival info with departure info for some of its citizens and/or other legal residents and/or visitors. This would be less likely to occur if the government didn't rely upon airline collection and filings and instead used its own direct checks.