That's how it's done now.[1] But seeing wear on a hook is tough even with high resolution photos, because the wear is between hook and eye and doesn't show clearly until the setup is disassembled.

[1] https://youtu.be/7-JTqwUyD5o

Did you look at the photos of the hook, it should be visible to a proper inspection. That marketing video of inspections is either picked for nice panning shots, or is simply inadequate operation to make it look like they can inspect faster than they should to be effective.

Where a park can't be verified, its replaced regularly.

Replacing them every 30 years won't bancrupt anyone.

Can't you just infer it by how much of the original eye is unoccupied?

In the UK helicopters are used as drones simply aren’t fast enough to image an entire transmission line in a reasonable amount of time.

However unlike PG&E we take high resolution photographs of every major component on a transmission tower, and manually inspect and classify every image take. Images of this type would have identified this fault, at least once during inspections taken during the last couple of decades.

Source: Worked for a company that did these inspections.