And with due process they can be. DOJ whines too much.
At this time, only 10% of Apple iOS devices can Apple get into and then only for limited data. Any iOS devices running iOS or later is 256bit AES encrypted and one the user has the passcode, which Apple does not have. Without that passcode which, internal to the device, is entangled with the device's UUID generates the very complex AES encryption key, no one can decrypt the data in any non-astronomical time frame. If the user has elected to use a complex 16 character passcode using the upper and lower case alphabet, numbers, and symbols from the 223 characters available on the Apple keyboard, the key would be 140 characters in length. Using a key of that length would, running the math, require 5.62 X 10195 years, 5.62 undecillion years, to try every single possible key, using the fastest supercomputer array we have at our disposal today which can try 3 Trillion keys a year by brute force.
The half life of a proton is estimated to be only 1030 years and it is estimated that the Universe itself will be degraded into a temperature less soup of elementary particles by approximately 1080 years from now. . . and if your supercomputer still existed, it wouldn't be even half-way through trying keys!
I think the contents of your iOS device might be a tad moot way before then, don't you? At least you wouldn't be caring too much about it. . .