FWIW, they were charging $3/package for their initial launch at UWaterloo, and people were actually paying for it. You're right - probably not enough people for it to be feasible, but yeah, even some of us ('poor' students) were paying for it.
I would pay that in a heartbeat. Living in an apartment is a nightmare for receiving packages. I hate getting the missed package slip and then having to call and arrange for me to pick up the package at their facility 20 minutes away. I've had to wait 2 hours at the sorting facility for them to find my package before.
So to me, $3 seems like a steal when faced with all that.
Our apartment is awful for receiving packages... UPS and FedEx can't even get in the front gate. But I just get packages sent to work, so there's not a problem at all.
It makes sense for Amazon since they make money on all the packages. I would guess that purchases made through Google would likely be free at BufferBox.