As a consultant, I've been helping startups with their hiring process, and I've noticed, at this point, even very junior engineers, just starting, are expecting flexibility of schedule, and many are looking for work from home options. (I am not saying this is good or bad, I'm only noting it.) At some point in the past I think there was a bit more of an attitude that one had to "pay one's dues", at least for a few years, but now there is more of an assumption of work from home options being available. And even though Amazon is, typically, hiring a more experienced engineer, and paying more, than the startups I've consulted with, this is certainly the right move for them. It's good for a company to offer flexibility and to be very clear about exactly what is being offered.