I always find these things an absolute pain!
The kissing gate (yeah, yeah - tired joke) was designed for the purpose of allowing the passage of walkers, but not the passage of livestock. It consists of a half round or V shaped enclosure, between which is trapped a hinged gate. Swing the gate away, squeeze into the enclosure, swing the gate back, exit.
The name actually comes from the way in which the gate only 'kisses' the sides of the enclosure, rather than being latched, though it is normally weighted so that it rests closed to one side or the other.
It can't be left open by accident (as if :p)
It can't be tied or fastened open on purpose!
It doesn't need a latch
The word 'squeeze' might have been a bit of a clue here. Anyone who has walked with a rucksack of any size (or even worse, a toddler in a back carrier!) will know that these things are not easy to negotiate; the problem being, of course, that if they are constructed with a space large enough for easy passage of a person with a large rucksack, they are also easy passage for a sheep - because sheep are notoriously adept at getting out of places that they are not meant to get out of!
All things considered? Give me a 'climb-over' stile any day.