This isn't exactly the answer to your question P57 but it spits out of a program I wrote for amusement a while ago so it's easy.

Betting on the favorite over many years at WA
You get 88.77% of your money back from the bookie over 16000 races and 97.44% from Tabcorp (33.5% winners). This includes a lot of piddling races at minor courses, thus, I guess, the high return from tab favorites. - From NSW Tab you get 93.22% from 8750 races (31.5% winners) in the same period (these would be the more major races of course).

Always backing the winner on these same 16000 races - 613% from SP and 793% from Tabcorp.
Betting on the first horse in alphabetical order 62.7% from SP and 79% from Tabcorp.

This is probably not typical Australia wide, I have long suspected SP pays worse in comparison to TAB in WA than it does in say NSW.

I could probably do the same for NSW but would have to do a bit of programming.

KV