The airlines are giving out all the information, that's why there is no need to do an exit passport control.
From the US? I can't think of any outgoing passport control at all; not by land in a private vehicle, nor by boat.
So France has basically no idea who shows up from Germany or leaves via Belgium. The countries on the external borders are supposed to handle all that.
Now I suppose it's possible there is a lot of data exchanged in real time and so on, but it's also possible that is a complete mess and nobody really knows anything, especially about citizens (GDPR).
I have not crossed that many non-Schengen land borders, but as far as I remember it was the same every time, when going from France to England through the channel, Belgium to England by train, France to Switzerland (before Switzerland joined Schengen) and Canada to the US.
I have been to a few airports where you explicitly clear US customs at the departing airport before leaving for the US — Vancouver, BC and Dublin Shannon come to mind.
If you've overstayed your automatic 90-day Schengen area travel visa, a common hack for backpackers and such is to intentionally leave the Schengen area from someplace like France that's generally less strict about counting exact days than many other EU countries.
To be fair, I don't have much experience flying from the Schengen area to non-Schengen area non-US countries. It's totally possible this is all rigamarole that the US government pressures other countries to do.
I have heard of friends of friends who overstayed a visa and get found out on the exit gate (usually bringing a lawyer/embassy official to talk through things). This can lead to a (temporary?) travel ban to Germany and a fine.