there’s some related discussion here: https://forum.inaturalist.org/t/look-for-location-in-more-than-1-picture/3679.
most observations don’t have more than one photo. theoretically if you take a photo within the iNat mobile app, it does try to get a reasonably accurate location, if the user waits long enough after taking the photo for the device to get a good lock on the satellites. you could theoretically improve the chances of recording a good location a bit by having the phone start to acquire a lock on the satellites as soon as you start the app (rather than waiting until after you take a photo) – or at least providing an option to do so – but then none of this helps if you take the photo from outside the iNaturalist app. so in the end, the best solution – the solution that applies most broadly – is still probably educate users about how to get good locations on their devices in general.