Maybe it would be more costly, but the escalation would also provide the justification to strike down the population completely and simply murder all the protesters. Instead of reading about peaceful protesters being attacked you'd read about the military taking out insurgents.
Civilian militias have an enormous advantage over organized militaries. Guerilla tactics.
Yes, special forces employ them, but never the less, you’ll never see a special forces groups throwing IEDs on insurgent convoys.
Unlike civilians, organised militaries have rulebooks to follow.
This is true especially in authoritarian states with centralised decision making. See: the six day war. When communications were out, Arabs became mindless drones and the morale was in the toilet. Perhaps not the best example because that was organised military vs organised militaries. However, for Israel, everything was at stake. It was either victory or total annihilation.
I'm curious. What was the last anti-insurgent war we won? I'll list the ones where we lost: Vietnam, Iraq, Afghanistan.
Yes ordinary people in much of Afghanistan and parts of Iraq can get hold of firearms if the want to. It doesn't help them at all. They are utterly dominated by either the local militias in Iraq (Sunni and Shiia depending on their area), or by the Taliban in much of Afghanistan.
If arming everybody worked to promote freedom, then Iraq and Afghanistan would be free associations of local communities joining together to protect their liberties. That is clearly not the case, and it isn't the case in any country with weak government and pervasive access to arms. Guns everywhere make the weak weaker and the strong stronger.
Guns do not even the playing field. In practice they dramatically tilt the playing field even more in favour of those with a willingness and propensity to use violence.
In both cases, you'd read what the oppressor wants you to read.
It created an arm race between civilians and the authorities. The basic police in the US is better equipped than the military of most EU countries.