My mom is terrible about this and it drives me crazy. She calls me quite frequently and only ever uses speakerphone. She has an insanely loud voice to begin with and speaks even louder when she talks on the phone since it's on speaker. It drives me nuts because I have to turn my volume way down when she calls (and then remember to turn it back up when I'm done) since she's so loud, but since speakerphone often cuts in and out with what you can hear, I then have to turn the volume up, but then it comes back in and she's making my ears bleed. It's a never ending back and forth with the volume button to understand what she's saying.
She also sees nothing wrong with talking with me (or anyone else) on speaker in the grocery store, doctor's office waiting room, etc, and has no sense of etiquette when it comes to discussing personal issues in the hearing of others, including gynecological issues in graphic detail, past abuse she's experienced, intimacy issues in past relationships... All stuff I don't want to hear at all, let alone a bunch of strangers in Walmart. If you try to tell her to call you back when she's home, she either talks over you and ignores the suggestion or insists, "oh no, it's fine," and keeps talking. Even though I'm not physically there and barely get a word or two in myself, it still embarrasses me for her. She won't even hang up to check out at the grocery store and always uses self-checkout, so I get to hear the constant, "Please place your item in the bag, please place your, please place, please, please, please place your..." Along with her talking even louder to hear herself over that, and she of course always has 1000 items to scan and can only do it with one hand since she's holding the stupid phone so it takes 5 years for her to check out. I swear I want to find whoever invented speakerphone so I can re-route all of my mother's phone calls to them so they can experience the full torment of their invention.