You could modify your views to handle this.
But technically speaking if the CMS and MVC sites are set up properly, this URL:
https://domain.com/getmedia/15b542fd-e2ee-47e6-9212-c3fa733eb3a8/your-image.jpg
and this url:
https://admin.domain.com/getmedia/15b542fd-e2ee-47e6-9212-c3fa733eb3a8/your-image.jpg
should both work without issue and return the same path. So if they were copying the URL from the Media Library link, then tell them to simply modify the URL (remove "admin.") to be that of the public facing website. The image should work just fine and if they are already used to copying that URL it's a slight modification from what their current process is.