Public transport is a public service. Like roads, schools, hospitals, libraries, parks and gardens, etc.
Yet, they are considered a commercial activity. And this commercial activity is considered « in deficit » by public authorities. And so, we are told that users must pay more to « balance the accounts ».
How to fill the deficit? By increasing fares, reducing services, privatizing, making users pay…
Meanwhile, the deficit only holds from this angle: if we completely stop charging users, there is no more commercial activity. There is no more deficit, just a public service.