Automatic route recording

no, move iq only takes the time and the recognized sport. Like cycling or walking. It doesn't matter more

 I'm not sure if your title "Route Recording" matches the question about distance run but Move IQ does not turn on GPS and has very limited data.  Further to what Sievin stated:

"When your movements match familiar exercise patterns, the Move IQ feature automatically detects the event and displays it in your timeline. The Move IQ events show activity type and duration, but they do not appear in your activities list or newsfeed. For more detail and accuracy, you can record a timed activity on your device." 

If you wife is actually getting distance with a MoveIQ only activity then that is the strange thing.  Note that you can run a "full" activity and also get a Move IQ event from it.  Maybe this is what you are seeing.  Perhaps more details?  All manuals, FAQs etc from Grmin are very clear and consistent on the limitations of Move IQ.

I'll skip over the statement

CarstenS said:

But why should the flagship not be able to do it if the Venu 2s can?

as I would then need to list the things the Fenix does that the Venu does not.  

I am familiar with the function of Move IQ. However, with the Venu 2s, you can additionally set that activities are automatically detected and started after x minutes. This function is missing in the Fenix 7.

CarstenS said:

with the Venu 2s, you can additionally set that activities are automatically detected and started after x minutes. This function is missing in the Fenix 7.

Exactly. And that will certainly not change.

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-7-series/311295/garmin-7-does-not-auto-detect-activities-where-is-activity-tracking-now/1507856#1507856 

Just out of curiosity: Does move IQ detect bike rides as well? I guess runs are relatively simple to detect, but I imagine it is very difficult to detect bike rides because there is no specific movement of the wrist involved. 

Yes - it works. Move IQ probably detects it because you keep your hands still and ride at a certain speed.