Hmm, that's fascinating, never heard of these before (though that's possibly because they probably won't be available in New Zealand for at least a decade
.)
I googled them and they appear to be a combo of
1) for people with needle aversion
2) safety as presumably needle can't come off afteruse, which presumably means
3) you can't use the needle more than once....
4) and extra plastic waste....
And it's nice to see that the only thing that's changed in the demonstration of injection technique in 50 years is that now they use apples whereas when I was a child everyone learnt on oranges...
Mind you, there was a recent poster here who said their pharmacist told them they had a needle shortage, maybe they are out of stock of the traditional "unsafe" ones....
I guess it's one way to enforce a single use needle policy....