Reflectors are another required component but isn't what this is about. The candlepower and color of the LIGHT is the issue at hand here. A red tinted bulb to meet those standards does not exist. The only way to do it is with a red lens or red LED's.

The reflectors are required of course but they do not need to be part of the light housing. You can glue them to the bumper as long as they are there somewhere.

 

Thats what I would have done on the green truck, imo.

 

Yes,that's true. A red bulb in a clear lens lights up nowhere near as bright as a clear bulb in a red lens.

Here's those same tail lights on my beater Mazda. This is with the running lights on. Visible in the day, but much more visible at night, yet still weaker than what it would have been with the stock lenses. BTW,the bulbs I was running were clear bulbs with red gel caps. So yeah, I can see these being completely illegal,which they were.