Jerry Garcia & iTunes

I found and purchased Jerry's first solo album today, "Garcia" on vinyl. It's an original 1972 edition. While in the store I pulled out my phone and went to iTunes as I do with a lot of the old vinyl albums I'm thinking of buying and sample a few of the songs. Thus time however I hit a snag. I can't find any of Jerry's solo studio albums anywhere on iTunes. I've googled it and found no explanation either. I found one article written in 2012 listing Garth brooks, frank Zappa, kid rock and a few others who aren't on there, but nothing about Jerry Garcia. It has the entire grateful dead catalogue as well as many collaborations jerry did with others but none of his solo studio albums. I believe he had 4 or 5 of them.
Does anyone know what the story is behind this. Thanks!