Riding fixed gear is like driving without brake lights

Spoilsport.

But the point stands that a lot of cars will slow down without brake lights showing anything.

I can slow the car pretty effectively by matching the revs/declutching down through the gears, which I do because it's fun- but of course it doesn't show any brake lights as you slow.

If there is someone coming up behind me I'll use the brakes in order to illuminate the brake lights to give warning that I am slowing.

But- that's because people are lazy and look for visual cues that they expect to see: no brake lights, no slowing happening.

I would not expect non-cyclists to pay any attention to a cyclists leg-speed in order to judge speed.