maybe it's because here in Socal, particularly the LA area, there are a gazillion freeways and to say "head down the freeway" would beg the question, "which freeway" so we replace freeway with which one we're talking about

we have in the LA area the 405, 5, 10, 101, 110, 90, 105, 710, 605, 210, 134, 170, 91, 60, 118, 14, 2... did I miss any?

__________________
If you feel the need to bash/rag/insult/demean someone, please read this before you do. Thanks and have a great day!