Why would Qantas not be considering Melbourne to Shanghai?

Why would Qantas not be considering Melbourne to Shanghai? I have flown the route 5 times in 13 months and each time it is jam packed regardless of whether it's Air China, China Eastern or China Southern (1 stop)

Because MU, CZ and AC have lower cost bases and can offer cheaper flights. I think there's a lot more Chinese coming to Australia than Australians going to China.

I haven't found Chinese Airlines cheaper (by much if any) than Qantas on my trips

Qantas don't make money to PVG from SYD  (according to Qantas anyway). Wouldn't make sense starting another PVG in that case.

Bums on seats is only one factor in making a route financially viable (as smit0847 has eluded to).

Why bother if they don't make money?

Network reasons. Let's not forget that QF international hasn't made money in most years... if we took the why bother approach, they'd fly to North America.

It would be good if Jetstar started the route, especially on their B787 .

Then could stop over via SYD (MEL-SYD-PVG) so more opportunties for MEL-SYD domestic travellers to visit the First Lounge!