Yes. I work on an in-patient ward, predominantly. It's not an entirely infrequent situation. In hospital, all drugs are paid for by the hospital, so patients are not bearing costs. We will prescribe a medicine for when the child goes home, and then an hour or a day later, the ward will get a call back when the parent is surprised to see what it costs. They'll sometimes say that they can't afford it and that they need a different medication.
That really does happen.