I hate to be cynical (really, I do) but this seems like a clear attempt to soften Amazon's current public image as being a horrible place to work. It seems like all surface/headlines and no real substance. The headline makes you assume "Oh employees are going down to 30 hours a week but still being fully paid." because in order for this to be really noteworthy at all, it would have to be, right? But that's not what this is. They are basically just knocking people down to part time but keeping benefits, apparently?
That doesn't seem like a good deal to me. I don't want a 25% pay cut for 25% fewer mandatory hours of work. As other commenters have pointed out, unless this comes along with a reduction in responsibilities and/or increase in staff, the same amount of work still needs to be done. And most exempt employees already work more than 40 hours a week.
Add to this the fact that the Washington Post is owned by Bezos, and this just seems like a clear PR stunt to me, and a lame one at that.