If you ask around (self included)historically many people that wear HA’s hear better on a speakerphone. Speakerphones are not very private and as mentioned earlier they do not go well in a work environment unless it is a conference call.
Once again Bluetooth gives you privacy and security. FM would be like the early cordless phones or even a party line where someone you may not even know can just listen in on a conversation.
Many people consider concerns over privacy, paranoia. I suggest you might find it challenging to learn about or even help arrange a surprise party for your wife over a speakerphone.