Cars need the blinkers to actually 'blink' orange. You can't get clear bulbs to blink orange, you can get orange bulbs to blink orange though. But people don't want orange bulbs in their clear housings. That's the egg yolk look.
But what people figured out is that if you take amber/orange bulbs and coat them with silver.. that the bulbs will appear clear with the corners, but blink amber as per the law.
Seen here: