This puzzles me as well, especially after recently acquiring an LX. As stock with only bigger tires/free sensor adjustment, you are getting 5" extra clearance when in high mode. The thought of spending 5k+ on the initial purchase price for an LC, and then spending 5-10k to achieve that kind of lift for 34s, just sounds crazy unless i had a ton of money (which i don't). Even if i had the ton of extra money to statically lift an LC that high, it still wouldn't match the LX because you can't lower it back down to get your nice geometry/handling back after leaving the trails. Like someone said earlier an LC is only better if you go nuts on upgrading the suspension, and even then it is only better on certain trails and even worse off in other areas like highways. AHC gives you some of the best of both worlds, which is perfect for someone like me who wants to go in and out of civilization as i please. I like that i won't stick out as much when i go back on the pavement.
I could side with
@TeCKis300 all day on this just on the AHC part alone, but i think the only thing that hasn't been pointed out is that for someone like me with a lower budget than most, that it's either i go LX or i can't afford a 200 series. I paid 18k for mine and with 2k more in tires/rims upgrades, it will still beat a 25k LC with 5k more in suspension mods. That's before you get into the world of extra luxuries that is found in the LX. 20k for a base vehicle then just add overland mods, i can manage. 30k for a vehicle then add overland mods is too much for me, especially if you consider that the cheaper one is still the better vehicle.
With that said, i'm guessing the biggest reason is that one carries the "Land Cruiser" name, and one does not. I don't think the average person knows that the LX570 is essentially a Land Cruiser, and even the ones that do fall victim to undervaluing it by underestimating the AHC system. Many people have looked specifically for "Non-AHC" LXs and LCs for the same reason, and because of that something that should add value to the vehicle actually ends up bringing down the value.
Overseas where people have the option of adding AHC to their LCs, many do and many pay a lot of extra money for it. I think people are right in that Lexus Depreciation and quantity sold does have a big part, but ultimately i think it is a fluke that is a result of the average person not knowing/not understanding that the AHC LX570 is not just a 200 series, but an upgraded 200 series; and definitely not a downgraded 200 series. I think people are mistaking an upgrade for a downgrade because they assume many things like worse reliability, but as time passes people are waking up to the fact that AHC is very much reliable.
Another thing to consider is the kind of people who look for used LCs; they obviously don't have the kind of money for a new one so money is a concern. When money is a concern, Lexus isn't usually a place where people look as opposed to Toyota. Also many used LC owners likely have been fans of the "Land Cruiser" name for a long time as well, which reiterates the point about one being a "Land Cruiser" and one being an "LX570". The Land Cruiser name has developed such a big following that there are always people specifically looking for used Land Cruisers, but nowhere near the case for LX570s; assuming the average person does not know Lexus makes a Land Cruiser.
I think as people become more educated on just how capable the LX is and that it is essentially an LC, that they will learn to appreciate it more as well as value it more. Until then, i would highly suggest that anyone still looking consider an LX if you have not already done so.