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.