Hey Kate! People can repost their reviews on here from other sources by using the Lunch This tool, it brings over reviews from any other website and posts it on here. Sometimes the ratings don't match up since we have a -5 to +5 scale. So, when it's a 3 on other sites sometimes it's a +1 on here.

I'm sure they don't mean it but, maybe they haven't had a chance to change it on here yet or they may not know. Maybe you can rate the review and leave a comment with your concern on their review, you'd just want to make sure it's the same reviewer as on Amazon and Goodreads! I'm sure they'd be grateful for your attention to detail and that they have a good answer for you :)

I will echo the other answers.  No, it's not weird at all!   I have posted the same review on Goodreads, Amazon and here.  The rating does not carry over.  New viewers see the same review and grade it differently.  Also, all three sites you mention do have different rating features so of course they would be different. 

Yes, I do check what I am writing and my own star rating.  And that's the way, uh huh, I like it, uh huh.

I'm certain the writer knows what he's doing. On Amazon, you can get trolled fairly quickly by rating something very low, whereas Lunch seriously seems to be far more for intellectually discriminating minds ... and far less trolls.