Why aren't they a thing? Surely breakers with LED indicators would sell like hotcakes?

Illuminating the space behind the panel door?
Illuminated when tripped?
Illuminated when'On'?

SqD has the red flag.

Not sure what you were getting at with this question.
You're implying wasteful?
40 or 100 LEDs of appropriate indicator brightness would be about 5 watts max.

Wouldn't they be nice in a dim or dark room?
I'd put in 3 LEDs... green ON, red tripped, blue OFF (so that no light at all would mean trouble)

Ida know. I'm a bit old fashion. I rarely trip breakers, I'm standing in front of the panel anyways so I just look. Even with the flag on the QO or the handle is in the middle or put 50 LEDs on it, I'm gonna test it with my meter anyhow.

Years ago there was a brand called "Trip & Light" or something similar, they seemed to be based on a ITE/Siemens breaker, but have not seen them in years, guess they never caught on.

There something about the trade. The buy in on anything new is tough even when it forced down our throats through a code update.

I hear that some of the new AFCIs have diagnostic LEDs that help you figure out whether you had an arc trip, a GF trip or an over current trip.

There are automotive fuses made that light when blown, makes it easy to find in todays vehicles with dozens of fuses. They are quite pricey however.

Nick:
I was curious as to why you were going here.

You explained the trio in your reply.

5 watts max on 24/7 (<1Kw day) would be roughly $4.00 +/- on a monthly bill at .15 per KWHr.

Greg:
Yes, the Siemens line of AFCIs have LED indicators. That's one brand that I know of.

I'm not sure what advantage the lights would have over the indicating handle.
In a panelboard there would be so many lights in it that you would have to walk right up close to see which light was which. Once you got that close it would be just as easy to look at the handle position.

Although I did have a rather odd request from a paperpusher at the Chicago Park District that wanted me to provide a pilot light that would go on when they lost power and go off when the power came back on.
LOL

So did you give him a quote for a miniature standby generator to run the pilot light?

But seriously it would be possible with relays and a battery.

I built a little box,(including an LED), that screamed bloody murder when the power went out, until silenced. Then again when the power came back, until switched back to normal. My friend told me that he just happened to wake up early that morning during a power failure. He switched his mom over from an O2 concentrator to bottled O2. The thought of what might have happened to his mom scared the hell out of me. I was late for dinner because I was building the box to take over the same day. After his mom passed away, I gave the box to my stand-in dad, who had started using supplemental O2.
Joe

SqD has a clip up on U-Tube showing exactly these new fangled circuit breakers.

They answer the need to figure out what's been causing the trouble.

I expect this style to entirely replace the current favorites.

http://www.youtube.com/watch?v=-SXGM-BfcW0

http://www.youtube.com/watch?v=ECi6An24KbQ

Everyone needs to view these short clips.