If you live in an apartment building, other people can hear the contractor scanning the parcel too and if they are dishonest they will be quick.

I now leave my door partly open when waiting for a parcel so that I hear when it arrives and thieves are also less likely to steal if the door is open because they could be seen...

I was actually surprised when Aramex left my parcel downstairs and I thought it had been stolen when I saw "delivered" and could not find it - and then I found it downstairs several hours later and nobody had stolen it!