Sydney's public transport mask mandate stays but is lifted elsewhere

http://www.matthaydenblog.com It's a relief that now masks are not mandatory in Sydney's shopping centres and supermarkets. But they still remain on public transport. So what exactly is the point? These arbitrary half measures make no sense IMHO. It seems to me that if this virus is such a threat, and the masks are effective, shouldn't they be worn everywhere that is crowded?