BOO - " ... you do not innocently stumble along child pornography at all ..."
I have to disagree.
As you may have seen on other threads, some years ago, I was contracted by Microsoft to check out a list of websites for child pornography - a lot of sites are set up using Microsoft software, and they were undertaking a sweep in what was to become - although we didn't know at the time - Operation Ore.
I was given software that wouild allow me to visit and view a site's content without leaving any trace of my visit - this being because any sites of this type would be hper-sensitive to 'outsiders' and any detected traffic would mean the sit would be shut down and re-opened under another identity.
Abuse sites 'hide in plain sight' - they have innocent looking front pages, and the dogy stuff is behind, if you know it's there - but that does not preclude a perfectly innocent browser finding the site.
One of my sections was 'car enthusiasts', and one was 'food' - and under two completely innocent fron pages which any browser could find, I found Level 5 images on the inside pages.
So - yes it is possible to accidentally find a site like this - they are unlikely to be tagged with 'distressing images this way!' - but -
the actions from there are the browser's own.
Finding a site by accident means you click off it and report it to the police.
Exploring it further and downloading makes you a child abuser, and hopefully within the reach of legal process.
So yes - these sites can be accessed in all innocence - someone looking at Vauxhall Corsa engines or various kinds of nuts could have found two of the ones I discovered, but I clicked back and reported them, as I was required (and delighted!) to do - anything else is a different darker set-up entirely.