>The thing about the U.S. is it's not a handful. They have more guns in civilian hands than people. It would be very easy for U.S. civilians to arm literally everyone...

You're still labouring under the false assumption that, were an oppressive government to come to power everyone would rise up against it. That's simply not true. A sizeable chunk of the population would perceive said government as a "good thing" either because; it smacked down on some section of society they detested [cf. Nazi Germany and the Jews], they profited from its existence [cf. Nazi Germany and companies like Krupp, IG Farben, VW, etc], it elevated them from nonentity to a position of authority [cf. Nazi Germany and people like Heinrich Himmler, etc.].

And there would also be a sizeable chunk of the population who would just keep their heads down and hope that, if they didn't draw attention to themselves, they'd survive it all.

I mean that is pretty much what the current policing system depends on. Enough people who might be tempted to step out of line are just frightened enough of the possible consequences of getting caught, that the numbers who actually do transgress stay just about manageable.

How much more so would that be true if, instead of a "civilised" interrogation, followed by a fair trial and a justified prison term, the consequences of raising your head above the parapet were being dragged out of bed at night, whisked away somewhere to be beaten into confessing and then put up against a wall and shot?

I think you're massively under-estimating the number of people who would either support an oppressive regime, or would just knuckle under and wait for things to improve.

You could be right. I hope not!