https://en.wikipedia.org/wiki/Cavalese_cable_car_disaster_%281998%29
The low level training routes are specifically there for just those purposes. The bomber crews must have the training needed to penetrate enemy defenses if there is ever a need. These routes have been around for decades and are marked in aviation charts. It is a required part of bomber crew training to maintain their proficiency in very low level flying.
That cable car accident was due to hot-dogging and was not permitted.