One small externality of Amazon's approach to business optimization: Amazon so closely tracks its drivers that they're strongly incentivized to shave seconds off of every delivery. When they come to smaller apartments with push-button buzzers, they'll push every button immediately, not just the buzzer matching their package. It disturbs every occupant, but there's the chance that they get buzzed in a few seconds sooner because a different tenant is hoping for their own package, is expecting a guest, or accepts that this is how Amazon works.