Why cant I gift some films ?

Hi,

So I wanted to share a film I watched with a friend. It's called "Fluidride: like a pro"

When I search for it in the iTunes store, I can see it, I can buy it, I can rent it, but no option to gift it.

I already own the DVD myself, I thought buying it for a friend might have been an easy way to share it rather than lending them the physical disc.

I searched for another random film like "Wind River", and sure enough it give me the option to gift it. So it seems like some do and some do not. Why is it so ?