Mastadon (and the Fediverse in general, to some extent) has problems with discoverability and the average user finds federation confusing. People tend to either use microblogging to see what's going on with people they're interested in or to broadcast their activities to a large group of people, and Mastadon currently doesn't fit that niche very well.
I understand and sympathize with Rob on a spiritual level.
Maybe it's Newcastle, New South Wales, Australia? They would be using Australian dollars, with $ as the currency symbol.