"We have advanced weaponry, but we don't spend life at the point of a gun."
Weapons are not reducing in cost and size every year. It's possible in principle to know if someone has a weapon, and to exclude them from a given small area. Weapons have only a few specific uses (defense, hunting, target shooting or sparring, crime), and don't gain hundreds of new kinds of uses every week.
The soaking of our society in computing power and recording is proceeding rapidly, and I don't think it can be stopped in any given jurisdiction without severely impacting the ability of that jurisdiction's business to compete economically. The ability to enforce arbitrary restrictions on what individuals can record implies a police state, even if the police are kindly for now.
I notice that people now calmly mention that they partially disagree with Brin, rather than dismissing his transparent society as completely beyond the pale.