Even the much respected Howletts and Port Lympne collections in the Uk have had to bow to the 'Great God' of commercialism in recent years.
Howletts hasn't changed much (its only about 50 acres) but at Port Lympne they now have a large drivethrough area (the African Experience) with African savanah animals as an addition to the main park(you pay extra) and I believe there's also a hotel for overnights too.If you look on the website you can see they have expensive deals for weddings, breakfasts, shadow a keeper etc- all in order to make extra money.
Some years ago there was a rumour Port Lympne might have to close or be sold, and it seems this increased commercialism has been the only way to keep it viable. Maybe for Australia Zoo too commercialism is their main option for the future, though its not one I like to see happening anywhere.