At Microsoft, the standard practice is that if you say you're leaving to take a job a company they consider a competitor, they cut off all your access at the end of the day, even if your manager wants you to stick around for knowledge transfer. If it's not a competitor, it's up to you how much notice you want to give. If you say you're leaving but don't say who your next employer is, they assume it's a competitor.
Facebook was classified as a competitor, Amazon was not.
Facebook was classified as a competitor, Amazon was not.