Why U.S. tech giant Apple and others are putting billions into affordable housing

Natalie Sherman for BBC News:History teacher Leon Sultan was raised in a San Francisco that working class families could call home. That place has, for the most part, vanished.
The city is now the centre of America’s thriving tech industry, with some of the highest housing costs in the US. Homeownership is in retreat and homelessness is surging, alongside newly-minted fortunes. Mr Sultan, and many others, blame the changes on the Bay Area’s tech boom, which has created vast wealth di