Generally, no. Mechanical ABS came about in the late 1960s, but cars didn't commonly have ABS until the early 1980s. But putting it in there anyways so people could use them if they needed to is much better than the alternative.
Traction control and anti-lock brakes are both assists, even though assists that actually do exist in the real world. The game's insistence on setting them to 5 by default has nothing to do with whether or not the vehicle you're in has them in real life but rather is just simply a universal game default. It's there to make the game easier for you on all 1000+ of the game's cars and not just on the ones that actually have them in reality.
A rl '69 Corvair (not in GT5, much to my vexation) had an option to come with a device (a "TC" device) that would shoot a squirt of de-icer on the rear tyres. Cool.
