The Qantas Kangaroo route via London to Paris adds 2 hours onto an already long trip. Originally Qantas weren't allowed into Paris as a tit for tat for not allowing Air France into Australia. This changed when British Airways bought into Qantas.
Although Air Mail postage between say the UK and Australia is fast, mail from France is typically 10+ days as only Air France takes French mail out of France whereupon mail is dumped out in the open in Singapore where it is nobody's responsibility until it's eventually put on a Qantas flight. Not enough people effected. No votes in the issue. 'Who cares' is the attitude.