Stepping through the video in more detail, I did miss the preface that it was the interior that they had done no restoration on; the fault of ten-second video jumps and my not backing up to the start of a voiceover segment.
Checking other videos of the Luchs, a video showing Panzerfabrik’s Luchs appears to have mesh over all the grilles, while the video of the Luchs at Miltracks 2017 and the Saumur Luchs show mesh over the side grilles, but none at the rear, although they appear from the identical camouflage pattern to be the same tank, so that’s not increasing the sample size.
Museum Ordnance Special Number 22, “Luchs” Panzerspaehwagen II (2cm) (Sd.Kfz.123) Thomas Jentz. Page 14.
Note the damage to the rear screen next to the right edge. Then tell me a tourist did this damage to the “museum installed” screen, just so they could shove their candy bar wrapper in there. Nobody is running around in Bovington with a crowbar or wire cutters just to dispose of their garbage inside of a tank.
There is little doubt that these screens get severely abused in combat, holes from shrapnel, HE round impacts, mortar rounds, etc. Sometimes they get blown off completely;
The vast majority of photographed wrecks are missing all their tools, many missing wheels, tracks and anything else the crews or other troops could salvage and remove. Then came the farmers, scrap merchants and other civilians looking for anything of value. The photos we see of such pilfered wrecks are poor evidence of the vehicle’s original appearance. With only about 100 of these vehicles being built, finding pristine, war-time photos of the engine decks is probably not possible. Maybe a post-war examination of Normandy chicken coops would turn up our apparently missing screens. Outside of that, I put my trust in the statements made by Thomas Jentz.
We might all be overthinking this; perhaps somewhere, say, on the Eastern Front, such and such a unit with the Luchs, suffered from debris getting into the rear (as there was no mesh as part of the original build). Perhaps, a unit commander got his Instndsetztruppen to fit a mesh, and reported this up the chain of command – or at least the Instandsetztruppen commander did (being under remit so to do). In due course, through the maintenance chain of command, perhaps an instruction was passed back down to all fronts where the Luchs was operating, saying that where there was a likelihood of debris getting stuck in the engine compartment via the rear apertures (Norman apples?) then units were to fit mesh as they saw fit.
It might just have been as coincidental as that. The military mind, in a perfect world, would ideally conform to Befehl ist befehl, but often is far more flexible than one might think; even a seemingly rigid army like the WW2 German one.
And if no one can dig up evidence (pictorial that is) one way or the other confirming all Luchs had a fit here but not there, then personally I wouldn’t give a damn what others thought of my model(!)