[green-bottle]

I don't have much of an idea about Windows or OSX. Regarding Desktop Linux, I think I wouldn't be far off if I said it has no desktop security model. The permission system on *nixes (and Linux by inheritance) were formulated in the context of it being a multi-user system with multiple people logging in via a terminal. Your data had to be protected from access by unauthorized users. I don't know if security aspects of running untrusted or unverified programs was even considered which are significantly more important in the current context.

I think Flatpak is trying to improve Linux application security but still has a really long way to go compared to the likes of Android and iOS.