Probably because they’re being added individually by uploaders/taggers that feel like it, rather than it being a concerted effort to tag all the coloured genitals on the site. It’s only natural that they would tag what they care about or happen to notice rather than do every type at once.
[character 1], [character 2], shipping
the image which I’ve shown didn’t have the ship tag
Floating heart
should be aliased toheart
one is ♥ and one is floating
heart
s are “floating” so I fail to see a difference.Looking up “Fluttershy, Rainbow Dash, Shipping” would be one to add the “Flutterdash” tag?
FlutterDash
-> Fluttershy
, Rainbow Dash
, shipping
ButterBlitz
-> Butterscotch
, Rainbow Blitz
, Fluttershy
, Rainbow Dash
, FlutterDash
, rule 63
, shipping
floating heart
imply heart
instead. The difference in the tag usage is fairly similar, but not absolutely the same.