I will say that for the most part, 8n that particular thread the women are spread open. Their legs are open and in most cases in a position that makes entry easier. Or they are bent over and "presenting" which can have the same effect. As I stand in my kitchen if I were to reach down between my legs, I'm 100% certain my labia are doing an excellent job...
...Yep, they are earning their pay.
As soon as I bend over and spread my legs, everything becomes more accessible for you fellas...
Check and check.
I'm not sure which picture you're referencing though, but I'm betting this is the case.