> In process sandboxing was definitely one of the worst ideas attempted in the early days of Java. None of my jobs in the last 10 years have ran with the security manager enabled, as it's just useless. I'm suspicious of any modern technology attempting to do the same thing, as it's just hard to get right.

I think Android has done a very good job with their permissions, which seem quite similar to me. Am I missing something?

Yes, properly limiting permissions is difficult, and there can be bugs, but that's true regardless of what layer the security controls are applied at.