Why are OTA are so much cheaper than Qantas/airline direct?

[YSSY]

I recently purchased an itinerary NTL-BNE-DXB-FCO-DXB-BNE-NTL and found it priced at circa $1300 on EK flight numbers and $1390 on QF flight numbers. I tried booking the same through the Qantas website and it priced up at $1900 and then tried calling Qantas to ask if the could match the online price and they priced it up at $2500. I know that Qantas offer the Price Promise, but I really wasn't going to gamble on that in case they decided that my flight didn't meet their requirements somehow.
But I've seen this a lot when searching for flights, the OTA prices are hundreds of dollars cheaper than going direct, whereas when booking hotels I can often get the price matched or even beaten in a quick phone call or e-mail.
I do't really understand why the airline can't sell their own tickets cheaper...

 

[RooFlyer]

Sometimes it's there conditions attached to the on line ticket that allows then to be cheaper. Won't be noticed by the punter until the poo his the fan and they find they are stuffed. Or they on line company had bought some inventory in bulk ( again, with conditions) and saved some money, which they pass on.

Edit: or like'home brand', the airline sells at a discount to on-liners but won't discount their own brand.

 

[YSSY]

Sometimes it's there conditions attached to the on line ticket that shows then to be cheaper. Won't be noticed by the punter until the poo his the fan and they find they are stuffed. Or they on line company had bought some inventory in bulk ( again, with conditions) and saved some money, which they pass on.

Edit: or like'home brand', the airline sells at a discount to on-liners but won't discount their own brand.

Absolutely, I've always accepted that when I purchase a ticket using one of these big OLA that refunds, changes and any other issues are likely to result in a lot of hassle.
I've actually just experienced this with Netherlands based BudgetAir (albeit ticket issued in Sydney through their Sydney website), after I purchased flights with China Airlines which the airline cancelled due to Coronavirus restrictions, but I spent hours going around in circles with BudgetAir trying to get my money back, they wanted to charge me hundreds of dollars in cancellation fees because I 'CHOSE' to cancel. In the end I ran a chargeback through my credit card (Qantas Platinum) who told me they are doing hundreds of chargebacks everyday against OTA due to China/Coronavirus cancellations.

 

[ftm]

Often it is the pricing logic that the airlines put on their own sites. For example, Qantas will push you onto all QF codeshares, whereas a cheaper fare (quite legitimately, nothing dodgy) might be available if you mix and match QF flight numbers with EK ones. QF doesn't want to show you that because they don't get any revenue from the EK flight numbers, so they just show you the higher price. This often happens to the US as well, where Qantas will show the QF codeshares only, and not the QF/AA mix, which is often cheaper.

An OTA (or any agent) doesn't mind and will just show you the cheaper fare.