The current trend for rear light design, looking at you Peugeot and Vauxhall in particular, is a large lens with the tiniest amount of real estate given to the brake and indicator lights. Why is this slightly dangerous? Because from a distance they are correspondingly more difficult to see. If you are two cars behind and looking through the windows of the car in front, these type of lights are much more easily hidden by headrests and A, B or C pillars. So the advance warning that something it changing ahead is lost. And on some cars they are so close together they blend into one, see picture below. The indicator and the brake lights are on, not that you can tell from a still photo.
The lenses themselves are always plenty big enough for a larger area to be devoted to these important warning lights. Let’s make them BIG and add to road safety.