Ex m38
The wheel base of the tow vehicle is much shorter than the the wheelbase of the trailer.
The effect of this 'steering' is that the trailer wheels follow fairly closely to where the truck wheels went. How closely depends on the ratio of the length of the 'stinger' as measured from the pivot point on the truck---usually the center of the tandems, to the hitch as compared to the distance from the center of the trailer tandems to the hitch. If those distances are exactly equal the trailer would necessarily follow precisely in the truck tracks.
There is the telescopic part because the trailer is actually being pulled by the logs, and the hitch must elongate around turns.
Let’s not fixate on the loggers, we are travelers on this site. The logging example was given as an extreme example that shows that if the distance from center of rear axle of truck to pintle is equal to the distance from pintle to centre of axle of trailer then the tracking will be perfectly same.