iOS, on the other hand, restricts its apps heavily - they are sandboxed, can't access other apps' files (no ransomware) and need explicit user permission to meddle with their private data.
Now, yes, exploits exist, but look at macOS - Apple still controls developer certificates and can pull the plug on misbehaving developers. An alternative to the app store wouldn't be nearly as devastating as win32.
You raise an interesting point about Android malware. Does it stem from the fact that Android apps can access the filesystem?
