Ricky,
Cast treatment of fractures has been very successful for millenia. It is a true art, and takes a lot of skill. An orthopedic surgeon can't just slap some plaster (fiberglass) on the leg, it has to be applied just right, with proper molding in just the right areas, so that the fracture is properly aligned, using the principles of physics and three-point bending.
You are right in terms of the surgeon making more money with a surgery. He gets a big payment for a short amount of time, whereas with cast treatment, there are several small payments over a long period of time. And it can actually take quite a bit of time to treat a fracture by casting. The surgeon completed residency training, to learn about orthopedics. He went into the field because he likes to do surgery (and the money), so he is, of course, going to want to do surgery if he can (it's fun).
But, anyways. Since surgery has become so much safer in the past few decades, many patients (and doctors) sometimes don't think of it as being as dangerous as it really is. Many patients think, "Oh, I'll just have surgery and I'll be fixed, better than I was before I got injured, and I'll be back to "normal" in a few days". Not likely.
And, you are also correct, in that it takes a lot of dedication on the patient's part, it deal with a cast. In the past, there was no choice other than the cast. But, now, if you don't like the cast, you can always have surgery (up to a point). I know what you are going through. I was in a long leg cast for four months. I lived in a high plains desert, where the average daily high temperature that summer was around 110F. I got really buffed upper extremities from having to use the crutches all the time. My leg was like a pencil, the knee and ankle were really stiff, the skin was very soft (my leg hair was really long too), and I felt really weird without the cast on. It took about another month before I could walk with just a cane. It was about a year, before I got back to where I was doing most of the athletic activities that I had been doing before the cast.
Okay, in treating a fracture with a cast, the ends of the bones may not be reduced exactly (to within a millimeter or so). But, it is not necessary. As long as the overall alignment of the bone is correct, the offset can actually be several millimeters with no problems. An IM nail doesn't reduce a fracture perfectly either, there is always a little "play" and therefore offset.
It is okay for you to feel the bone ends moving a little. There may be a clicking or rubbing sensation. That will decrease as the fracture becomes "sticky". And, the slight motion actually stimulates the body to lay down more callus (healing bone).
In terms of you losing muscle mass while in the cast, that is true. But, you will also lose some muscle mass after surgery. Usually, in the progression of treatment, a long leg cast (LLC) will be left on till the fracture is partial healed, as it appears on x-ray, with a bunch of new bone around the fracture. The LLC is needed so the fracture fragments don't rotate or angulate during the first few weeks of healing. The knee has to be included to be able to do this.
Occasionally, once the fracture has become sticky, and is not likely to displace easily, the cast may be changed to a LLC that is partially weight bearing.
Then, the surgeon usually goes to a cast called a PTB (patellar tendon bearing) cast. Here, the cast is reapplied, but the knee is free to bend. The upper portion of the cast is formed into a triangular configuration, which still helps with rotation. But, it is constructed so that most of the pressure is taken on the front of the upper tibia (where the patellar tendon attaches). Thus, the patient can start to weight bear and move the knee. This helps with the knee joint stiffness and muscle atrophy.
Also, it is a well known fact, that by placing stress across the fracture site, it will stimulate the fracture to heal faster (Wolff's Law). So, weight bearing is a good thing.
You have now gotten to the point in fracutre healing, that most of it is done. It is just a matter of finishing it off. Usually, at this time, the cast is removed and a fracture brace is applied. This can be taken off, so that ROM of the ankle can be started and the muscles can be strengthened, while the body consolidates the fracture callus.
The general steps of bone healing are essentially the same, no matter how the fracture is treated.
As you can see, gettinbg a bone to heal is a lot more complicated than just slapping a cast on, or ramming a rod down inside the bone.
Sorry about the length of the reply, but you had a lot of questions. If there is something I missed, I'll be happy to try to answer it. Also, remember to ask your surgeon about things.
Good luck.