"As for commute, this much is true and is a particular problem in the Valley. For me, my commute is a 7 minute walk to work (in NYC). YMMV. :)"
I might be going way out on a limb here, but I think this kind of thing is a subtle driver of age/family discrimination.
What kind of workers are more likely to live by the office, and thus able to drop in on a moment's notice? Young, single workers.
What type of workers are less likely to do this? Older workers or workers with families who have to deal with commute/spouses/children/etc.