Why don't you we ever have a 100% full moon?

Because, technically, a full moon only lasts for a Planck time.

Here is an old article from Space.com from 2004 that explains it better than I could write it all out here for you. http://www.nbcnews.com/id/4402294/ns/technology_and_science-space/t/full-moon-merely-fallacy/

And here are some other cool things about the moon. https://www.space.com/11162-10-surprising-moon-facts-full-moons.html

Sometimes you just have to settle. For me, when we have a full moon, it’s full enough.

Because the mountains and valleys on the moon create shadows.

Thanks, guys, and gals, for your insight!
@MollyMcGuire I am okay with 99.9, I love the moon in all its phases.

I honestly won’t be able to differentiate between 100 and 99.9% so I’m ok with it..!!