For anyone reading this post do not rely on taxis being available that will either have a capsule or a bolt to put your own in. We were broken down late at night on the side of a freeway in Melbourne and no such taxi was available. The car had to be towed, it was pouring rain, we could not walk off the freeway, we had to get into a taxi. I had to hold him in the backseat of the car til we got home. Totally illegal I know, but apparently very common.
In Victoria taxi's have an exemption, so not illegal to carry a baby in the back of one without a restraint. Not sure about other states.