The finish system generically known as catalyzed polymer (there are several types) bears mention. This material is a clear plastic that starts as sprayed liquid and hardens because of an added substance, called a catalyst, which reacts chemically with with the resin. Catalyzed polymer is virtually the only type of finish used in guitar factories any more because it is so labor efficient.
This finish is also very toxic and requires special equipment and rigorous physical protection for applicators, including remote-air-supply breathing masks. Because of its extreme hardness, it is essentially impervious to abrasive polishes and therefore cannot be processed effectively after application. The worst deficiency of a catalyzed polymer finish, however, is that it is comparatively thick and must be so in order to end up level and glossy. Almost nobody thinks this is a good idea acoustically.
Catalyzed polymer finishes are sometimes applied and offer thin finishes; French finishes encourage damage to the guitar surface. I personally prefer the polymer for a classical guitar. My 00-17 Martin, ca. 1960s, has a finish that is so soft it is too delicate and dents easily. Sound isn’t always compromised especially when the guitar body and table help and the small Martin was not big on sound but very popular as opposed to the larger 0028C model, not really much of a true classical guitar. My student Ramirez was not much to talk about. Anyway, this is just to say that some of us like the protection that polymer offers. I don’t think the sound of my French classical is compromised by the polymer finish enough to wish it were a French finish.