It is not nearly as widespread as your claim. Has this happened? Yes. Every brand except the store brand on the grocery shelf is on the certified list. https://www.aboutoliveoil.org/21-olive-oil-brands-certified-for-authenticity Just buy this and you'll never have to worry.
Depends on what I am serving the predicates which Olives are served. Now green olives are very common around here and served in wine bars. So we have an overage of green olive consumption