Depends of the teams, some teams have good crowds. In NZ there are 2 teams with good crowds: Crusaders and Chiefs. This is because Canterbury and Waikato are rural areas with long tradition in Rugby Union. Highlanders is in a small town in the South of NZ, Dunedin (only 120,000) with many students from the University of Otago so that's an impediment to them. The most emblematic cases in NZ are Blues and Canes, they are in the biggest cities of NZ so is very sad to see small crowds flocking to their games.
SA has 3 big teams: Bulls, Sharks and Stormers. They have good crowds, the others teams (Cheetahs and Lions) have interesting crowds. SA is the SANZAR's member with the highest attendance, for this reason, year after year they get more power in SANZAR. In 2016 they will have 6 teams, one more than NZ or AUS.
Australia is a very different situation, they are the only country among countries with rugby tradition, where Rugby League is more popular than Rugby Union. So this is a big obstacle for them, even NRL isn't the most popular professional sport in the country, AFL is the most popular professional sport in Australia. Despite this, they have some places with a strong tradition in the Union as Brisbane, Canberra and Sydney. Among those 3 cities, Brisbane and Canberra have interesting crowds. Last year I spoke with the community manager of Queensland Reds and he said that Union is very popular in Brisbane, even he said that attendances of Reds are similar than Broncos (The NRL team of the city). Of the 3 big teams, which have lower attendance is undoubtedly Waratahs but from what I saw, this year has improved somewhat, I hope this is a sign that the Union will grow in Sydney. Melbourne and Perth are the cities with less tradition in Union but Force has an interesting crowd this year. I think the Rebels' situation is more difficult because in Melbourne the most popular sport is the f**king footy (Aussie Rules -AFL). However, Aussies from Perth appears to be more open and willing to give an important place to the Union, I hope Force continue improving to strengthen our sport in Western Australia.