When Meg Whitman was living in California and running first eBay Inc. and then HP Inc., the idea that Africa had some role to play in her businesses rarely crossed her mind. “I literally thought about Africa 1% of my time,” she says.Such inattention is common at US tech companies, which generally decided that establishing significant operations on the continent wasn’t worth it, considering its unstable governments, oscillating tax regimes and patchy digital infrastructure. Changing that calculus...