What's the difference between Park Brake Set & Brakes On? Is one the selector and the other the brake pads? I hope they also have words and not just colours.
But back to some earlier comments. Some manufacturers have decided in their wisdom after committee meetings and historical events, to spend money, voluntarily, to include these lights on modern a/c; similar to DRL's & hi-level brake lights before they became mandatory. It would seem this is deemed sound investment to avoid expensive screw ups. I suggested it might become mandatory, but on reflection, it could be considered by EASA & FAA not to contribute to flight safety. Any screw up is only a financial penalty to the airline and/or ground handler. When I suggested why it doesn't become more widespread that was shot down on the basis of cost; and yet we are told modern Boeings & Airbuses have them installed, voluntarily. A few bucks above the lowest U$60m price tag seems trivial. On a U$180m hull it is negligible. Seems common sense has a low price threshold.
Have the modern B737 family got them fitted? Remember the cargo fire extinguisher debate. It was not deemed necessary as the original design Class D? was still the same, and it was going to be too expensive to retro-fit the world's fleet of mediums. The debate was caused by an unlawful act by one carrier. However, the design was incorporated, at significant cost, to all new manufactured. And the last cargo fire on the class worldwide was.....? The last attempted brakes on push back worldwide was......?