I haven't read this either, but the flange(?) of the wheel, the part below/behind the rail, is on the same lever as the point where the wheel contacts the rail

I haven't read this either, but the flange(?) of the wheel, the part below/behind the rail, is on the same lever as the point where the wheel contacts the rail (v), but further from the axis, so it's moving further (>v), also opposite the direction of the train's forward motion, so total negative speed, in the frame of the rail/ground. This is why a train is picked over most vehicles, which operate as you describe.