Brian, your right about the first base coat systems in North America being a lacquer base, however, the Europeans (Sikkens, Spies Hecker, Glaseruit etc.) had been using true base coat systems for about a decade or more before the North American paint manufacturers tried to catch up...Dupont came out with a Lacquer Base coat system called Hi Tech if I'm correct. CIL's base coat system was called...believe it or not...2K and so on. The Evolution of base coat in North America happened when companies would buy into each other to gain North American market share...ICI bought CIL's automotive paint line...Glaseruit bought into RM and later in the 90's Spies Hecker bought into Dupont (or vise a versa). The lacquer systems did not require the base to be sanded before top coating with a Urethane 2K clear (it would have been impossible to paint a BC/CC metallic if it would have to be sanded between base and clear).
This is what I remember of the history of Base Coat in North America and how difficult it was to represent a North American (makeshift) base coat system in the late 80's and 90's against some of the European manufacturer's truer base coats.