Twobets, your figures show that there isn't too much difference with Place divvies between Unitab and NSW TAB. I've noticed that the NSW TAB when showing a divvy of $1.04 in early betting that it ultimately pays an acceptable price. Maybe because people bet around it causing it to ease. As you say this is also not unusual with Unitab.

However, I'm surprised with Betfair. I've found generally that the lower the TAB price then the better with Betfair. And if you are betting only short-priced horses then this is where there is the highest liquidity, which should mean that there is money behind the price offered. Of course this may not apply to some of the more obscure mid-week races.