Some states in Australia have an education system that leads to mis-use of the term "college". This might be a peculiarly Tasmanian thing, since each Australian state tends to do its own thing, so I'm not sure if it is where the misunderstanding is happening (Dave is in NSW, so possibly a very different system).
High school goes to about 15 or 16 years of age, then you leave high school and go to a different school for years 11 and 12. This used to be called "matriculation" and later, the "higher school certificate".
In the 1970s and to a lesser extent in the 1980s, most of the students who went on to years 11 and 12 were doing so in preparation for university. Now it's pretty much expected that everyone does it. I think the big change happened in the early 90s when the government stopped allowing 16 year olds to go straight onto unemployment social security (welfare / "the dole"), but they could get a small welfare payment called "Austudy" if they stayed at school until they were 18 - a sly way of making the unemployment figures look better without actually creating any jobs, but hopefully it has improved some people's education.
Many of the schools that exclusively offer years 11 and 12 have the word "college" in their names, which leads local people to say "I went to college" if they did years 11 and 12 (or if they started year 11 and dropped out after the first couple of weeks). On dating sites, people often tick the "some college" box, when this has a very different meaning to "college" as defined under the American education system.