The problem with these devices, for the government, is that the people _might_ come back, but this time with tools designed to defeat these devices (such as guns as explosives). If that happens, it can be very bad (for both parties).
Overuse of these kinds of things is...dangerous for the government
I mean history says that’s indeed the next logical step
Governments, by definition, have legal access to anything they can get their hands on.
That depends on where you put international law into this. Since 1945 it has generally been considered that there's a limit to the actions that a sovereign country can take. International law might work primarily with treaties rather than 'conventional' laws, but there are already parallels with national legal systems. We have a kind of international legislature (the United Nations General Assembly) and a judiciary (the International Court of Justice).
The people can and should act as a check on the social contract they have with their citizens
Technology also attacks this front, through mass surveillance and disinformation. Which is really what we’ve been seeing in the past 20 years. More and more, the focus is shifting to the “source”, the human minds who demand change.