Speculation: because the heads of those companies think that surveillance is just peachy and it's their business model? That is certainly the case with Facebook

Speculation: because the heads of those companies think that surveillance is just peachy and it's their business model? That is certainly the case with Facebook, which acknowledges that they try to encourage sharing and break down norms surrounding privacy, then take the new norms they've created, treat them as a baseline, and extend them further. They think this is good. And it's not like the NSA is going to compete with them for advertiser $, so no bigs.