Even worse, in some countries disassembling proprietary software to analyse its behaviour can be prohibited (at least they write this in EULA). And modern OS h

Even worse, in some countries disassembling proprietary software to analyse its behaviour can be prohibited (at least they write this in EULA). And modern OS have no protection against backdoors: desktop OS allow apps to do whatever they want, mobile OS like Android have privileges separation but don't allow user to control Internet traffic: you cannot run iptables or ban an app from accessing the network.