Yep, security is a massive problem. We just lost a bunch of cameras recently despite sturdy security boxes etc. Euan's links provide some very useful perspectives on what's been (or is being) trialled to reduce theft and damage. I had an idea of using something like the dye cartriges used in some shoplifting prevention methods (the cartridge bursts if an attempt is made to remove it - http://www.losspreventionsystems.com/alpha-ink-tag-an-anti-theft-device-...). Obviously, the idea would need to be adapted to get it to work properly on a camera, but the principle does seem to deter shoplifitng (apparently). Tamper sirens might also be a deterrent in some cases.
As Paul Meek mentions in the Conversation article Euan linked to, when it comes to motivations for stealing and damaging camera "...there is no intellectual evaluation of the activity". A few cases probably relate to drug growers or other nefarious activities. Code locking, even when advertised, doesn't seem to prevent theft, and expecially doesn't prevent damage. Trying to get to the human behaviour itself could probably help us understand how to prevent it. For example, there are growing privacy concerns (see another article from Paul: https://theconversation.com/the-privacy-problem-with-camera-traps-you-do... and also: https://arstechnica.com/science/2018/11/camera-traps-designed-for-animal...).
Close collaboration and discussion with local communities in the areas of cameras is therefore a good idea in some cases, especially if it alleviates privacy concerns.
I also think that camouflaging cameras probably has the most merit, as trying to make a grinder-proof (or stronger) security box seems ultimately problematic, or tracking stolen cameras only adds to the cost (even though trackers are coming way down in price). Disgusing cameras as something no one is interested in or notices (e.g. a rock, a tree branch etc.) is better than trying to stop theft/damage in my opinion. I once made a camera that looked like a limb of tree (basically I put it inside a PVC tube and covered it in bark) and I am pretty confident no one ever saw it.
Anyway, a very useful discussion so thanks for posting. Looking forward to reading other ideas.