Without meaning to sound snarky, you'll have to ask the people who create the materials that refer to them that way.
However, the word "consumer" does focus you on the business of healthcare, including price, accessability, affordability, etc. You can have a great product, but if your consumers can't find you, get to you, or afford you, you might as well not have that product. Thinking of patients as (would-be) consumers of healthcare might make this more clear.
I realize in countries with socialized medicine, this might not make sense.
Student or Learner