How is the absence of drones in TOS accounted for?
The DOT-7 drones appear in the early seasons of DISCO in the mid 23rd century. I know, modern show serving as a prequel to TOS puts things out of whack. However, they are canon.
I account for them by ignoring Discovery, personally.
I account for them by watching the first 2 seasons of Discovery and recognizing it's terrible.
You never saw them use a probe?
Also, the entire episode "changeling"
The hologram vs drone wars wiped out both technologies
They were happily working off-screen. We don't see most of the ship's functions.
An autonomous drone would be too close to a "pre-warp" species, so the Federation is forbidden from interacting/using drones.