I'm sure, and it's not hard to confirm - Insurrection made about 22 million, Nemesis just under 19 million on their opening weekends domestically. Given that Insurrection would go on to make seventy million and Nemesis only forty-three, it's pretty clear that Nemesis collapsed on the basis of audience response to the actual film after it opened.
I saw every Trek film on opening night in the Washington DC metropolitan market, one of the larger urban areas in the U.S. (far from the largest). There were "packed houses" on opening night for two - ST:TMP and ST:TWOK. Bear in mind that in the early 1980s "wide openings" were not yet customary for all commercial movies - if you wanted to see either of those films on opening night, you had a choice of about four theaters in the area. The most successful movies of the 21st century, by contrast, rarely sell out theaters.
So, I'll see your anecdotal evidence and raise.
Star Trek films have always made the vast majority of their money in first run in the United States itself, something which the folks running Paramount know all too well and have spent considerable resources trying to change during the nascent Abrams era. Just because the movie does particularly well or badly in a single foreign market, like Australia, isn't likely to tell one a lot one way or the other about how much money it made or how popular it (or Jennifer Lopez, for that matter) are in the United States, because it represents a very limited and nonrepresentative subset of data relative to the whole.
