The misunderstanding is because of confusion between “free” as gratis versus “free” as Libre. Open access is “free” so people assume it is gratis (I.e. cost nothing). People assume that things thar cost nothing are not as good as things that cost something.
Two things worth pointing out to people with such misconceptions:
1. OA is not gratis. Someone always pays for it.
2. Articles that cost money are not necessarily better. Closed access publisher produce a lot of crap. You only need to look at El Nashie’s debacle at uni of Alexandria for an example.