Comment by artimaeis
The Phoebus cartel didn't collude just to make the light bulbs have a shorter lifespan. They upped the standard illumination a bulb emitted so that consumers needed fewer of them to see well. With an incandescent you have a kind of sliding scale of brightness:longevity (with curves on each end that quickly go exponential, hence the longest lasting light bulb that's so dim you can barely read by its light). The brighter the bulb, the shorter the lifespan.
Also, incandescent lightbulb lifespan is reduced by repeated power cycling. Not only is the legendary firehouse bulb very dim, it has been turned off and back on again very few times. Leaving all your lights on all the time would be a waste of power for the average household, and more expensive than replacing the bulbs more frequently.