I think a more apt analogy is that the doctor gave you your blood test results (just as they'll give you your prescription without the PD), but refused to chara

I think a more apt analogy is that the doctor gave you your blood test results (just as they'll give you your prescription without the PD), but refused to characterize the color "A deep shade of crimson with a touch of scarlet", which is something that you can do yourself with a little knowledge. So you're still getting the information that requires special training or licensing, and you can get the other information yourself if you really want it.