I frequently record tracklogs with my phone, but have been less diligent about tagging photos with the result. This is easy to do for an individual track (well, notwithstanding tracks representing e.g. several years of location history - I tried that and LR didn't much like it), but laborious to process a large backlog. In my case, my backlog largely results from laziness, but this may also apply to people who do a lot of travelling and don't always have the opportunity to apply these processes as they go.
There seem to be many tools (and questions here related to) automated tagging of photos to an existing track log, but none I have seen where this automation is designed to scale to a few hundred tracklogs and many thousands of photos without a lot of user intervention.
As it stands, using Lightroom, for example, the process seems to involve a lot of manual steps for each individual track, navigating back and forth between Map and Library modules to select the right photos... most comments I've found describe this feature in rather more generous terms than I am tempted to use myself. I'm aware that there are other tools that will do a similar job, but I've not found exactly what I'm looking for.
It should be possible to point a program (which could be a Lightroom plugin for instance) at all of my tracklogs and photos, and have it tag any photos taken at times for which tracks exist, without needing any intervention. As long as the set of tracks and photos are both from a single user with the camera(s) and logging device in the same place, I don't see any major reason why this wouldn't be straightforward to implement. In more complex cases where tracks and/or photos might not correspond one to one, design of UI would be more challenging (needing for example options to exclude photos taken with a particular camera from the process), but this seems unnecessary for a great many users.
I suppose there's also potential for 'jet-lag', with photos taken shortly after moving to a different timezone being potentially ambiguous.
I can appreciate that there are also liable to be discrepancies resulting from plain old incorrect timestamps (resulting from user error like forgetting to adjust for DST), so it would be desirable to have a GUI with which one could interactively review the tags before applying them... devil is always in the details, but essentially the information is there and the computer should be able to do this job trivially. If I don't find something that does what I want, I'll probably try to write a script that attempts to do it completely automatically with no GUI whatsoever, or a Lightroom plugin or simple app with some GUI.
Obviously I'd rather not have to reinvent the wheel, though.