Re: It comes down to power supply efficiency
Yes. Lots of lightbulbs do indeed have a standby mode, but I suspect not many people have them in their homes.
Modern 'Explosion Proof' lighting assemblies use standby to prevent sudden state change from potentially causing a spark (and explosion if it's a bad day). A convenient side effect is that the bulbs last 'forever' as they never experience the cold to wide open state change that kills other bulbs.
High intensity HID spotlights, emergency lights, construction lights, makeup lights and shitloads of specialty videography and photography lights all have standby for the same reason as above and so that they provide their full power and proper color of light immediately after being turned on. Old, pre-standby lights of those sorts experienced significant color shifts as they 'warmed up'. The end result was that it was hotter than hell where those lights were in use because they were left on to eliminate the color shift period.
Most streetlights in the US have standby. Mostly for filament longevity purposes. There was a big grassroots movement here in the late '90's when the proles discovered that their streetlights were sucking so much power and in older lights were actually on constantly, at reduced levels, by virtue of current leaks, but nobody knew it because you can't see them burning in the daylight.
I'm sure some home lights have standby as well, but most people have no need for such things and would never even go looking for them.
*New lights in reef aquarium setups have standby too. People probably do have that sort of thing in measurable quantities.