There is a great deal of information in "The Hull Truth". It boils down to who does the job, and what materials are used. Some are just better. Some are scams. To have a top notch job costs about $100 a foot. Some detailers charge close to that for an excellent compound polish and wax. The coating is expensive, but so it the labor to do the prep work. I paid about $75 a foot for a really good detail job on the Caracal.
My Ford Explorer has a good ceramic coating job, and it is now 3 years old, and still looks just like new. I probably will get it done again at some point.