I wonder what would be the odds of Village having at least as many different boards where it's worthwhile, yet Shanty Town getting picked up more often because of its boards randomly showing up more often.
Shanty Town may also just be more distinctive. It seems like either one is probably going to get bought if it's the only cheap village, so when won't they be bought? For Village, other villages can often take on its same purpose but better. For Shanty Town, on the other hand, its potential handsize increase is not shared with the other villages, so it can stay prominent. The effect seems worse than a reliable +1 Card, but not if you have an excess of Actions, either through other villages or just the board being filled with non-terminals. And those are precisely the situations where Shanty Town's village status would be least likely to guarantee it a spot in your deck. With that in mind, it really does make sense that it's a card you'd want to pick up a solid majority of the time it's available, doesn't it?