Why Does Tremor Sense See Flying/Floating Champions?

So, this has kinda bugged me since she came out, but why does Rek'Sai's W passive Tremor Sense detect all of the flying/floating champions? If we are to take the name as descriptive of the ability, then she's feeling vibrations through the ground and locating based on that. All of the flying/floating champions would not create vibratory loci at their location (you could make a case for the flying ones displacing air which in turn buffets the ground imparting a vibration, but the magically floaty ones?). If such champions were not noticed by Rek'Sai it would square up the ability thematically with it's effect and description, as well as add in a (i think) really interesting bit of gameplay that Rek'Sai players and teams would need to consider.

A (maybe?) complete list of champions that would not be detected: Anivia Cassiopeia (do snakes make detectable vibrations?) Corki Galio Janna Karthus Kassadin Kayle Malzahar Nami (she seems to have a personal river which I would credit with vibration dampening properties) Nocturne Sona Syndra Vel'Koz Xerath Zilean

Edge Cases (Not sure/Partial Immunity?) Evelyn (in stealth mode at least - goes with her super stealthy persona) Kalista (do spirits physically tread the earth?) Lissandra (not sure how her locomotion actually works) Lulu (while W'd) Rengar (in ulti - stealth should be stealthy. Besides, once Rek'Sai's around, all the stealthy champs would figure out how to fool her) Rumble (in W dash) Shaco (In stealth mode) Talon (ulti. stealth.) Thresh (something about spirits) Twitch (stealth mode) Vladimir (in pool. blood's weird though - shear stress might be enough to create vibrations from the motion) Wukong (stealth)

Anyways, thought i'd throw this out there. My apologies if this is the wrong location for it - i'm new to the forums.

~RaiKirah