That sorta explains the “way no TouchID” on reboot Q. I always had at the back of my mind. I think courts have ruled that giving them a password is covered under the 5th amendment self-incrimination rules. I guess no rulings on “forced fingerprints” yet. I guess Apple’s lawyers for looking out for me with the “force you to enter a passcode on reboot/turn-on” feature! ;-)
The courts have ruled that fingerprints are fair game for law enforcement for ID purposes but not for unlocking purposes, but that is a gray area where an incidental fingerprint is concerned. In other words, they can't use fingerprints they take directly from a person for ID to unlock anything that is locked with a fingerprint. But they are undecided, or actually have not really ruled, on fingerprints found elsewhere being processed, converted into a facsimile finger, and then being used to unlock a fingerprint sensor lock.
The courts are also undecided about grabbing your hand and pressing your iPhone/iPad to your fingers attempting to unlock your fingerprint protected device, as that is not a "fingerprint taken for ID purposes." There may be a case someday about that, but it hasn't happened yet.