I would assume running wires to a few cell towers considerably cheaper than running wires to many villages. Indeed, isn't that why cell phones themselves are much more common than landlines in rural Africa?
No, it's because many developing countries "skipped" a technology. They missed out on land-lines because they were undeveloped, and now they have electricity and infrastructure, they jump straight to cell phones.
Jeesh, it's like you're missing the trees for the forest here. Skipping technologies is the pattern but there's a reason for pattern.
Developing countries don't skip technologies out of a desire for hopscotch or something. They skip wired tech because copper wires are expensive, their expense doesn't go down over time in contrast with the increasing sophistication of chips. Conventional phone lines and electrical power are both wired tech. Thus both are harder in third world conditions.