Most modern gauges are controlled by the ECU and not directly off the sender - my old Disco 3 would sit resolutely in the middle - until it got really hot when it would shoot into the red! Monitoring the live values off the sensor (And reading the specs TBF) then normal was something like 85-95 but it wouldn't move the needle until it was over 100 and 107 being the light (Or similar!)
I've never seen my BMW move off 100 (Mid scale) in the 20odd months I've had it (Once warm obviously!) - whatever the weather or what the heater is doing.
The good old days, its a direct connection so they do move about.
The reason given by Land Rover is something like, not panicking the owner if the gauge goes up and down!