I still say that the numbers they give aren't really useful to support those points.
You don't feel that a list of stolen vehicles by model year that very consistently shows 15+ year old vehicles being the most commonly stolen vehicle (within the same make and model
!) to reasonably support what I am saying, which is that older vehicles are more commonly stolen than new vehicles? There are a LOT more 5-6 year old Accords, Camrys, Rams, F-150s, etc. still on the road than 15-20 year old vehicles of the same make. Those makes have all seen either consistent production or increases in production over time (full size trucks having a exception during the 07-12 time frame due to gas prices). And, of course, many of those older vehicles naturally are sitting in a junkyard, not in a driveway.
I don't disagree that there are many factors at play here and that the "study design" of my citations is probably very lax, but you're looking at an extremely consistent trend across many different vehicle types on nationwide scale. I'm not cherry picking data.
And, of course, I'm not basing this entirely on those numbers, but also on the realities of vehicle theft which is different from most consumer goods theft. Like I said the economics and logistics of vehicle theft clearly favor older cars. Tell me, why would you steal something that is (relatively) very difficult to steal that you can't easily profit on? Whole stolen vehicles are extremely difficult to resell due both to technological barriers (VINs, digital DBs, etc.) and law enforcement (government tracked ownership, etc.). Legitimate car dealers and purchasers won't touch something that is at all suspect. Further, there's no parts market for new vehicles due to warranties -- car manufacturers won't be buying your chop shop's grey market goods. New cars are simply a low value/ROI theft target.
Compare this to, say, electronic gadgets. Any electronic gadget more than a few years old is effectively worthless (can't be resold for more than a pittance), and there is no particularly strong effort made by society to stop theft of those types of things. Your laptop doesn't have its serial number and ownership history tracked in a central government database, it can easily be wiped and resold, etc. So naturally thieves target the new, shiny versions as those are the highest value/ROI targets.