I have an unsatisfying and quick answer for you Stephen – you simply will no solve this problem. Other staff WILL keep uploading photos in the incorrect way, and unfortunately no amount of training can overcome to reality that managing photos is not their core business, and they are simply trying to do it and get on with their lives. Ultimately, any system you implement, from Sharepoint to Schoolbench, requires administration, and somewhere between daily and weekly, it is likely you will have to be in the system re-tagging groups of photos. Now, having said that – you WILL have particular staff members who take pride in proper tagging, etc, and they are your champions. Also, the facial recognition and date tagging in these systems does mitigate SOME of the problems you have, because there are alternative ways to search for photos.
But long story short – it will not solve the issue you present. It will however ultimately be a better photo management system, and I have certainly seen that first hand with Schoolbench. It is not perfect and there are gremlins, including imperfect facial recognition and some interface quibbles, but their support is very responsive and the system is still ultimately an improvement.