When my boyfriend went for his hearing aides (he lost his hearing at an Ozzy Osbourne concert in the 80s) they asked him all sorts of questions and then explained the difference between the models. He can change the background noise when needed and does use his phone with them. Some people would not be able to use their smart phone, or don't have one, and they would give them the lower priced versions. They are very helpful at the hearing center.
I have never had anyone complain about their hearing aides from Costco. They guarantee them and give you a loaner pair when they have to send them out for repair. Send your parents for a free hearing test and they can decide if it is right for them. Good luck!
BTW, you do have to have a membership to buy them.