Advice needed for my mother.

Hi all, looking for a bit of advice. I'm my mom's caretaker and I'm concerned about her teeth. She is a 62 yo with Parkinson's and diabetes (and a myriad of other health problems) former smoker and her teeth are awful, chunks fall out sometimes when she eats. When she goes to the dentist he just fills them up and sends her on her way, she's missing a lot of molars and has a partial on her top teeth that doesn't even fit properly (it squishes all the way to the top and she always complains it's hard to chew). Her dentist will take one tooth out at a time but won't give her dentures, which I believe at this point she needs. Is this okay? I feel like he's just doing it to get money out of her but I don't know because I'm (obviously) not a dentist. She likes him because he's "nice and cheap" and she's seen him for years. Any advice is appreciated, thank you!

PS, sorry for the wall of text haha