That's very much the point. There's more to the cost/benefit ratio than just ticket price and the provider's profit margins. There's also the cost to the public of people not using buses: road congestion, which adds to everyone's commute times; the productivity impact of those longer commutes; the need for parking spaces when cars are used; the cost of that parking; the opportunity cost of those parking lots not being used for something else more socially valuable such as housing; the externalities such as additional noise, pollution and fatal accidents; the reduced disposable income that results from more costly (at point of use) options.

Most bus routes are already subsidised, as demand is often low in a rural area. Maybe there’s enough demand for a couple of services per day, but that’s inconvenient. Subsidies mandate minumum service levels, but don’t cover the full operating costs, so fares are necessary.

£2 per journey is not usually enough to cover costs, so the remainder is paid as another subsidy.