Vegas lines are based primarily on the perception of how gamblers will bet.
Vegas wants the money gambled to be as even as possible. They live on the 10% 'juice' - not on the hopes that one team beats the line.
Show me one Vegas bookmaker that tries to favor one team over another by encouraging action in one direction, and I'll show you a soon-to-be broke bookmaker...
I'm in the hospital with my wife, daughter, and new baby girl or I would link to you the that suggests you severely underestimate vegas.
There is compelling evidence that Vegas inflates the score of the favorite by about a point, knowing that most bettors will simply bet the favorite. This single point increases profits by something like 50%.
If you remind me, I'll cite the source, study, data and conclusion when we get home.