In a similar vein, if you want a really good book on the topic, Stiff: The Curious Lives of Human Cadavers by Mary Roach. Incredibly fascinating, thoughtful, and well-researched.
For anyone wanting more information on body donation, I would recommend the book:
Stiff: The Curious Lives of Human Cadavers
"For two thousand years, cadavers – some willingly, some unwittingly – have been involved in science’s boldest strides and weirdest undertakings. They’ve tested France’s first guillotines, ridden the NASA Space Shuttle, been crucified in a Parisian laboratory to test the authenticity of the Shroud of Turin, and helped solve the mystery of TWA Flight 800. For every new surgical procedure, from heart transplants to gender confirmation surgery, cadavers have helped make history in their quiet way. “Delightful—though never disrespectful” (Les Simpson, Time Out New York), Stiff investigates the strange lives of our bodies postmortem and answers the question: What should we do after we die??
Great book on the topic.
https://smile.amazon.com/gp/product/B00421BN2C/ref=dbs_a_def_rwt_bibl_vppi_i0
Mary Roach is a GREAT author for pop science (my favorite non-fiction genre besides food memoirs).
One reason is that a person's body shouldn't become the property of the state on the moment of their death. If your mom died in an hour you might not want organ harvesters showing up to strip her of her organs like you might strip an old car for parts. It should be the individual's decision, not the government's.
Another reason is that some people may not like how their organs will be used. In the US you cannot specify something like, "I want my body to be used in the Body Worlds art exhibit" or "I want my spleen to go to a child who will be saved by it". Nope, all you can do is say donate or not donate, you have no control over what is done with it. Your cadaver might end up in a crash test, or be used to record the rate of decay of a human body under certain conditions (for forensic research), or your head might be sawed off your body and be used for teaching plastic surgeons how to perform facelifts. To learn more check out the book Stiff: The Curious Lives of Human Cadavers. It's a great read.