Lol, that's not always the case. But in some circumstances it could be based on jealousy, if the girl isn't attractive other girls might give her photos attention to try and make her feel better.. And then assume that the attractive girls doesn't need attention because she's already attractive and should therefore be confident, which isn't always the case. It also depends on their social status as well, how many friends/followers they have. But there are tons of those relatively hot 'instafamous' girls, so they obviously get attention.
if you are one of those average, pretty girls who gets her photos ignored... maybe they know your personality. All you've done here so far is slut shaming and hating about other girls. If I don't like someone's personality, I won't like her pics even if I think she's pretty.
Also, who are you to decide if someone is pretty or not, who deserves attention or not? Maybe they are not as ugly as you think and you just have a different opinion when it comes to looks.
The reason less attractive girls get a lot of attention on Facebook is purely emotional. The more attention they get, the better they feel about themselves. That's typically why people give them that attention.
Hot girls on the other hand get that attention not because they need it but because they're God Damn Hot!
I feel like anyone stuck in-between looses this attention because they're neither too ugly or too attractive.
She has more friends/she likes other people's posts a lot and they reciprocate.
the type of slut that want to be a slut but can't be a successful one and instead of trying to improve their "slutness" just keep trying to bash other well succeeded sluts. Thirsty. And you're ugly maybe that's why your photo is being ignored.