this is correct. the only way i know of for regular users to get the information is to scrape the photo page that sbushes notes above. this is available only for your own observations.
for what it’s worth, there has been past discussion about different ways to create new functionality to provide this data (ex. https://github.com/inaturalist/iNaturalistAPI/issues/188), but i don’t think there’s consensus on the best approach for this, and it sort of seems like although staff would have no objections to some third party coding this so that it could be merged into the code, staff probably wouldn’t prioritize that effort for themselves.