I'm not certain that drivers that miss stops always (or even usually) do so deliberately. Concerned about the cyclist whose path is closer to a sound wave rather than a straight line, whether the pedestrians hanging about near a crossing actually want to cross, the thump-thump-thump of a bottle coming down the stairs, being late because the level crossing was down because two trains had passed, the intermittent fault light that comes on for a second or two at a time, the noisy group of school kids on the upper deck who are up to something (I could go on). So very occasionally they might forget to stop - particularly if there is no physical stop pole or are new to the route. If they are not slowing down, 'This stop please' - other contributors have indicated why the driver might not have heard a ring. Drivers are human, they occasionally get things wrong, its no big thing - and, in my experience, are usually apologetic.
The dictionary definition of a mantra is a statement or slogan, frequently repeated. There is no implication that the slogan is true, or is believed to be true! (Evidence - every general election that I can remember.)
The mantra comment was aimed at the "bad management and greedy shareholders", but maybe I was giving drivers too much benefit of the doubt. This is probably because its a very rare problem in my experience, despite all the other measurements of deterioration in recent years.