Why do they do it? What is the source of this? It looks to me like Google and the manufacturers jumped on the EU regulations (European Union's Radio Equipment Directive RED) and went completely banshee with it. They claim that they have to do all kinds of things like close bootloaders and prevent sideloading, while in reality RED is pretty vague and does not explicitly require it: "(d) radio equipment does not harm the network or its functioning nor misuse network resources, thereby causing an unacceptable degradation of service;
(e) radio equipment incorporates safeguards to ensure that the personal data and privacy of the user and of the subscriber are protected;
(f) radio equipment supports certain features ensuring protection from fraud." I really don't understand the motivation to go full throttle instead of doing the minimum to comply. It will not cut their costs or bring them more customers...