[@The Revenant]
Up to this point, all technology was reached by conventional innovation, research, and development. Much of it was spurred on at the Immortal's suggestion, since she came from a considerably more advanced civilization. For example, Midhaven's waste-burning disposal plant functions as power source for the nearby forge and mill. Since she doesn't know exactly how electricity is made, the system is an entirely mechanical one.

To cite a few more examples, ice tribes up north worked out how to generate electricity through chemical means (i.e. batteries), but they use it in metalworking processes to make aluminum and never thought to use it for modern functions. One of the forest tribes learned how to make airships a while back, and now live almost exclusively as sky-nomads.