The fact that the storage media that this dog can find contain anything but Veracrypt volumes proves that (most) criminals have terrible opsec. Most people who own CSAM are ordinary people, teachers, plumbers, truck drivers etc, not hackers, programmers and IT technicians.

Child abuse is just like everything else, low-friction solutions are going to win over high-friction ones. If you have to get an Android phone and sideload a shady app to get E2E encryption, many people won't even bother. In the world where E2E is banned, half of the shady E2E apps would be police sting-ops in the first place, and the other half could be seized and turned against their users with a strategically placed update. Just like with money laundering, you don't even have to prove that a crime occurred, simply getting the list of all IP addresses of people using E2E would go a long way in putting those people behind bars.

Again, I'm not saying that this is necessarily a good thing, but it's undeniable that many children would be saved here.