The majority of cars sold are used cars. Yes there are some who won't consider a used car, but they are a minority (a large minority, but still a minority). The average car last 12 years, the typical new car is replaced every 3 years with a newer one.
A salvage title is only used when someone intends to restore the car, and then it goes back to a normal title once restored (or at least that is how my state did it 15 years ago - each state is different). You get the salvage title only to justify paying taxes on the actual value of the car (sales tax on a car is for actual value not the price you paid, so a salvage title is useful to prove it isn't worth what the book says) It will show up on CarFax as restored then. (though as you note most such issues never get a salvage title as they are not sold)
Don’t know what state or country you are in, but that isn’t the way a salvage title works in any US state that I am aware of.
A car with a salvage title stays branded with “rebuilt” or “restored” in all common scenarios. There are ways to wash them to unbranded, but most are unethical and involve retitling in different states and such, rather than simply restoring the car.
Regardless, unless dealing directly with the DMV, most people call a branded title a salvage title, or at least say something like, “the title isn’t clean”.
Salvage titles are restored wrecks. Back in the day when it was easy to get clean titles, people would steal cars and “restore” wrecks… or move parts from wrecks into stolen cars to launder them.
A salvage title is only used when someone intends to restore the car, and then it goes back to a normal title once restored (or at least that is how my state did it 15 years ago - each state is different). You get the salvage title only to justify paying taxes on the actual value of the car (sales tax on a car is for actual value not the price you paid, so a salvage title is useful to prove it isn't worth what the book says) It will show up on CarFax as restored then. (though as you note most such issues never get a salvage title as they are not sold)