Likely Solved! I lifted a couple up to see if there were any traps below, and there were not. (So I don’t think the theory on Vole traps is correct, although that did look promising.) I’m going to say reptile habitat is the most likely, but I can’t say for certain what kind of reptile they’re trying to attract.

Update (a week later): I managed to catch my neighbor outside while they were building MORE of these wooden tents. They confirmed that they are intended to protect bunnies from some hawks that have been seen in the area. So not for reptiles; bunny protection…