No worries. What AA gets out of it is the right to say that they fly LAX-YVR and to book people, especially connecting passengers, on that flight. If you're not paying much attention, all you see is a seamless connection on a single airline rather than a schlep from one terminal to another.

One reason the code share price is sometimes out of whack is that each airline has a limited number of seats in each fare category to sell. On your flight, AA appears to have sold out of the cheapest fares while Alaska is still selling them. AA is happy to sell you a more expensive fare, though...

On partners other than Alaska, the code share vs. non-code share often makes a big difference in terms of miles earned, but you knew that.

Michael