This F!@#$% ticket pricing rort has been going on for decades.
I used to fly from US to Aust and return often and the pricing disparity was often at least 200 USD on the ticketprice alone omitting the huge diff in govt fees depending which end you start the trip in. When that is added in its even worse.
Sometimes though in past 15yrs after converting the dollars it was often cheaper to fly from Aust to the US and back instead of the other way around.
Problem is the airlines wouldnt let you buy a ticket at the other end to use. That is ,have a friend book /pay for the trip at the US end, mail you the "ticket" so you could fly SY-LAX-SY for eg.
Don't know if that is still the case but that is what I was repeatedly told.