I think it may sometimes be required by the airline (or their insurers and attorneys.)
Aside from flights to the USA and Israel:
- British Airways has it at Istanbul and Nairobi.
- Swiss has it at Cairo, but Egyptair does not for flights to Switzerland.
- Correct me if I'm wrong, but I think that there are inspections on the boarding bridge for many flights at CDG 2E/2F to destinations other than the USA.
- The USA sometimes has this as part of its random, unpredictable scheme. This includes domestic flights with no ostensible risk. Certain airports tend to do it more than others (Denver, in particular.) I suspect that this has dropped off a bit due to staffing problems.