I often have the experience of going to a museum, seeing a painting I like, and then not being able to find any image of it online - let alone a highres scan. In my casual searches I've found museums generally don't share high resolution scans of their collections. Try to find high resolution images of famous, but not super famous paintings. It's often virtually impossible.

I remember in college my art history professor had a personal digital collection of high quality scans that he'd procure somehow that were impossible to find online. The data seems to be highly guarded, I'm guessing b/c it can be used to make merchandise

So my impression is that the Rodin Museum is not really the exception here