Why am I seeing these tranait reefer trucks for so cheap when high roofs are so expensive?

I'm just wondering why is it that a shitty mid or high roof transit 150 with 250000 miles on it still goes for 15k, but I am seeing plenty of used produce transit 350s for around 10k, and they have less than 200000 miles. It seems like any large van that could be used for trades, odd jobs, or van life comes with a premium. Even though it's just a bigger metal box, the difference between a low and high roof used is practically double, so why is it that this doesn't apply to the event bigge reproduce van?