AA codeshare to LAX/QF

any reason why I can't book the AA codeshare on Qantas for a SYD-LAX ticket. As in the AA codeshare doesn't even appear on Amadeus or ITA or American.com but it's a valid flight codeshare number

AA7298 which is the QF17 route that operates 1-2 weekly?

This is to do with the dark arts of codeshares. If they directly compete on a route they often don’t offer the other carriers codeshare. I suspect this is a moveable feast and varies according to route day of the week etc. It come down to the fine print of the agreement between the two carriers. Also The regulators object to it being such that there is no competitive difference.

I thought QF and AA were in a joint venture not a codeshare. A revenue sharing joint venture at that. So I'm not sure they compete at all actually.

A quick check shows they do not offer each other’s flight numbers just the code share. So the dark arts of (apologies) joint ventures come into play here. In theory there should be no difference but in practice I’m sure there are.