I guess the difference could also be more due to "layout space on Haven is tight". Also, a quick search through the Seaside rulebook (2E) does not seem to give a general rule for looking at set aside cards, this seems to be always explained in the card specific sections.
So with the intent to have players needing to consult the rulebook as little as possible, putting the "you may look" text on Native Village makes sense, as the player doesn't know which card they set aside until after the fact. If you are unsure, you might think you only find out what the cards are when you take them into your hand later (a mistake I made for Research, for example).
For Haven, the ability to look at the card is just a way to remind you what you put under it, it's not strictly new information. Nevertheless the rulebook spells it out under the section for Haven.
So the difference I think is based on a combination of what text would nicely fit on the card and where it was likely to clear up confusion.