Why are lighting disconnects only required on fluorescent fixtures with double-ended tubes? There are other types of fluorescents as well as LED's that have ballasts/drives that will need servicing throughout their lifespan. If shutting off the light switch leaves the room in complete darkness, most will service these fixtures hot even without a disconnect. How can this be considered acceptable? What does a "double-ended lamp" have to do with anything?

It is an interesting question. Maybe a proposal is in order if you can make the case.
I think the low fruit on the original proposal was office buildings with long rows of tubes that typically get serviced while they are powered on.

Over many years of 'maintenance' calls, I have to fess up that I replaced many ballasts 'hot'. Not much choice, most of the time.

Cut & cap the 'hot'; cut & cap the 'neutral'; cut the rest.

Yes, the disconnect is a nice requirement for safety.

If I remember correctly, some of the fixtures were wired thru the sockets, requiring a lamp 'in place' to make the feed to the ballast.

I think you're talking about the F96, F72, and F60-T12 fixtures.

The bulbs had single pins that connected 2 contacts in the unsprung lampholders. The other end of the bulb had a spring in the lampholder.

The contacts were connected between the lines and the ballast.

That's it. Now it all comes back!

The removal of the lamps served the same purpose as the pull apart disconnect, IF the fixture was wired properly.

Perhaps the thing about double ended types is that the pins on one end of the tube can be inserted whilst the free end can be touched. Indeed there is a temptation to touch the free end pins to check the horizontal alignment to ease fitting the first end.

Isn't that (ballast) scheme effectively banned by Congress?

I haven't seen those in years and years.

Tesla:
Could very well be! Although 'banned', there are still plenty in service.

'Remaining old stock', which is allowed to be sold/installed may also be available in some areas.

Geoff:
Yes, I remember using the bi-pins to orient the lamp to the socket.

I don't use the pins to check the alignment, but there are a couple of flattened spots where the metal end meets that glass that face straight down (or up) when the tube is rotated to the correct position that I use all the time.