Heather D. answered 12/09/20
Want to learn Adobe Creative Suite or graphic design?
I agree that it is a crazy workaround and I wish Illustrator were more intuitive in this sense. I think it has to do with picking up pixels vs. vectors and they haven't made the eyedropper to read "through" objects.
Two ways you can do this without a screen shot is either making a copy of your graphics, Object > Rasterize them, then eyedropping the area you would like. Make sure you drag your color into your swatches to save it.
Or, you can also do the same with Object ≥ Flatten Transparency, then eyedropping it. It's a pain to be sure, but it will at least keep you inside of your program. Hope this helps!