I am changing the name of this thread from "is match attendance just a US problem?" to the current one, based on what I have learned from people's replies. I had thought that tournament attendance was a big problem in the ATP, and that is why Round Robin was being tried out. But based on replies so far, that does not seem to be the case.
Meanwhile, what people have been saying is interesting to me. I had never known anything about these numbers before, and they are giving me a better picture of the size and attendance of tournaments around the world.
I had also based my assumption of low attendance because of seeing fairly unfilled stands on TV. But I have learned here that many times people are crammed in the outer courts and practice courts, while the televised courts may be fairly empty. Also, some of the time, the upper tiers are where the fans are.
So, please continue to contribute what you know of tournament attendance in your country or city. And if you have attended, how crowded did it feel, and where were people spending their time. Thanks for all the responses so far.
Below is part of what I originally wrote, which is mainly a little rant on tennis on US television.
Speaking for the US (well, actually speaking for myself), we have a very narrow-minded way of televising the matches, which tend to make it seem that if a US favorite is not playing, then the matches are not much worth watching. For example, interrupting matches in progress with interviews of US players; over-hyping US players; telling the same stories about US players ad nauseum; making it incredibly difficult to find even scheduled matches on ESPN, which are changed without warning to re-broadcasts of American players; the strange idea that US audiences don't really need to see tennis matches live, and are happy to see them later on, when the scores are known or, by effort of the fan, the result has been carefully avoided in order to have the more exciting experience of uncertainty.
For many potential fans, TV is the entry. If it is too flawed, then the stimulus to go to tournaments is diminished. As for TTC, I have never seen it because it is not available in the Bay Area of CA. I have contacted them several times, and they say when ENOUGH people do they will start it . . . this does not help the sport either.