I was in California in 1942 when it took two hours to drive from Long Beach to Hollywood. In the 1960s when they had freeways and still had a state speed limit of 55 mph. Everyone drove 80.
Now I live in Utah where the number of cars is at least four times that of the 1970s. If I am in Salt Lake City and want to drive to Centerville between 4 and 6 p.m., I can plan on an hour. I burn an hour's fuel to go the 12 miles.
It seems like plain arithmetic. You can't move half a million cars over our crowded freeways at 55 miles an hour. People who have worked all day long are not interested in leisurely driving home and enjoying the scenery.