Apple can decrypt iPhones for cops

Apple apparently has the power to decrypt iPhone storage in response to law-enforcement requests, though they won’t say how. Google can remotely "reset the password" for a phone for cops, too It’s not clear whether Google "resetting the password" for Android devices merely bypasses the lock-screen or actually decrypts the storage on the phone if it has been encrypted.
I also wonder if the "decryption" Apple undertakes relies on people habitually using short passwords for their phones — the alternative being a lot of screen-typing in order to place a call.