I agree about parts people, not being as knowledgable today, as in years past.
But, remember this. How many parts jockys were even born, when our cars were common on the road? "Back in the day", most parts people were "motor heads" to start with. If they didn't work as a mechanic, most at least worked on their own cars, before going into the parts business. Cars were less complicated back then, and basic systems were the same between car brands. I have started looking for a part time job, at parts stores, and if I get one, I will probably have a hard time with anything 2000 or newer.