I'm sure that's been thought of. People who walk, take transit, or bike to work probably don't want the hassle of lugging a package home if it's anything large

I'm sure that's been thought of. People who walk, take transit, or bike to work probably don't want the hassle of lugging a package home if it's anything larger than would fit in your backpack. Having stuff delivered to your home is a convenience. Hauling stuff home from work subtracts from that convenience. If I walk around my neighborhood in the late afternoon I see little Amazon packages on everyone's porches. No one seems to be stealing them. I can see people who will want this Amazon Key thing, but I can see a lot of people for whom this addresses a non-existent problem.