GUWonder

When it comes to the USG (and the CBP), it's not easy finding a more informed, skeptical and duly critical American than myself when it comes to these matters. Familiar with the notion of too much familiarity breeding contempt? Let's just say I'm a student of government.

I'm well aware of the US deporting US citizens, denying admission to US citizens and even willfully and knowingly preventing US citizens from traveling back to the US. That doesn't mean it's so prevalent as to be the primary concern for most people in the kind of situation mentioned by the OP. [Even on FT, I've put up links and otherwise mentioned these kind of things that the US has done to deny US citizens lawful rights and or otherwise harass US persons.]

It's a fact of life that US citizens enter and depart the US without US passports daily. Even for those situations where it is best advised to have the passport for the travel, there are routines that exist to make sure the US Government lawfully doesn't allow the US to deny admission to US citizens or to punish US citizens for returning to the US. Sometimes mistakes happen and too often the excessive measures of the government don't get met by justice, But that doesn't mean it's the most frequently experienced outcome for Americans in these situations -- it isn't.