it actually works great with less people. the problem is hitting that threshold requires regulation, which is a political impossibility except for special events.
So less people driving leads to less traffic, what a surprise.
I think that LA takes pride in its traffic, like some kind of shared struggle.
It is the only city I have lived in that has an implied 30 minute allowance for traffic delays. Everyone understands and you can use the excuse anytime or day of the week.
http://articles.latimes.com/1985-06-07/local/me-16088_1_traf...
as for the 3am traffic, that was probably night time caltrans work, or a drunk driving accident :(