Its not an instutional context its a state of being.........
ie we can say "going to the hospital"if we are refering to a destination. (the hospital down the road)
we would say going to hospital if reffering to being hospitalised.
just as we could say going to the bed. (the bed in the front room) or going to bed (to sleep).
equally going to court (attending a legal proceeding) or going to the court (going to a place where legal proceedings are held)
equally in education we drop the "the" from
school, college, university when reffering to the act of attending but use the the when refering to it as a destination.
hence "I went to the school to learn" could be simply replaced with "I went to school"