Aside from the obvious impossibility of privacy-compatible searches, I'd like to focus on the authoritarian excuse du jour, child sexual abuse.
How prevalent is it really? How often are children actually abused, in comparison to images of the abuse being circulated? Is there really an increase in child abuse over the last couple of decades?
It seems to me that this angle is especially unpopular to talk about among privacy advocates because most people will wrongly think that it is defending child abuse. Thanks to the magic of internet forums, I don't have to care too much.
In my evaluation, actual child abuse is happening at record low rates in the western world due several factors. The first is the secularization of society, reducing the influence and number of (always male) priests over large amounts of children.
Second, practical access to separation and divorce is much easier to women with children than it used to be. Wives can better protect their children from an abusive father than they could a couple of decades ago.
Third, a side effect of the campaign to eliminate gender roles and discriminations against women in education and the workplace is that men teaching young children have basically gone extinct.
Fourth, the hysteria about the problem has led all men to distance themselves from children in general, in order to avoid even the slightest suspicion.
So considering all that, what's really happening? We can expect rates of pedophilia haven't changed much. It's there genetically, and will be for the foreseeable future. The conclusion should be obvious: pedophiles have shifted from a society where getting away with abuse was a realistic prospect to one where it is not. So they do the next best thing and use pornography instead.
Of course, the material is still being made and the abuse still happens. But we've gone from a situation where e.g. there was one child being abused by each pedophile to one where that ratio is maybe one child to ten or a hundred pedophiles (or vastly more depending on how much the material was shared).
Am I wrong?