There are other unique abilities that can affect a Pokmons stats or moves, however, they are not given unique counters or placements
As Kotaku points out, the reason this is happening is because McDonalds doesnt have a unified rule for how to get a Happy Meal toy
There may be more ink on the back imprint, and therefore less ink on the actual stamp, but we forget that the ink is slightly bulging (compare it to a little bit of paint, or a lot of paint - the second means the overall result is thicker (actual thicker, not wider like with Thick/Thin 1st edition stamps ))
While we've seen soaring demand and prices on recent chases, they usually have an extremely high population - even in PSA 10, these days
I have to admit I gave extra points to this card because the flavor text is a reference to Star Wars and Im a huge fan, so that made me a little biased