Bob,
Well, the Hobart/KA (HOKA) dishwashers, with the big heavy cast iron wash arm, didn't have water heaters. They did have heated dry, however, but that's not quite the same. Not sure when the cast iron HOKA's were changed over to the stainless arms, or when the water heaters were added, but my '58 doesn't have an internal water heater - I doubt that any of the cast-iron wash arm models did.
The HOKA attempts to make up for this by purging the water line, sort of a pre-wash, before going into the full wash. The cycles are quick enough that I guess the water in the plumbing between the dishwasher and the water heater doesn't cool down much between purge and wash.
It's interesting that Frigidaire offers its water heaters in both glass lined and the cheaper galvanized tanks. My understanding is that galvanized was a poor option for a water heater tank, which is why you don't find them for sale today. The reason is that at higher temperatures, such as above 160F, the zinc coating reverses its anodic behavior, and instead of protecting the steel, it starts attacking the steel of the tank (the steel becomes sacrificial to the zinc). This may have been more of a problem for gas-fired water heaters than electric ones, since the gas ones probably had more localized hot spots on the tank walls/bottom than the electric ones with their suspended elements. But with temps above 160F, perhaps even an electric water heater might have a short life with a galvanized tank.