The article is about pop music. Not music in general. If you read far enough to see the statistics on various pop charts and musical festivals, you'll see the point they're trying to make more clearly.

They're promoted here as sing-alongs.

I live in a major city so the local venues here need a certain headcount before they'll book an event.

There's some very popular cover bands here but there are even less venues that can support them.

white ford bronco is the biggest one I know and their show sell out.