I've just seen it on my Ring doorbell.
17yr old DD had left the door unlocked for her friend so she didn't have to come down to let them in. Not uncommon.
Post arrived, including a parcel, during this time. When no one answered the door, the post person tried the handle, opened up the door and came into my home.
Granted, DD shouldn't have left the door unlocked, but it doesn't make what the post person did ok.
Just me who thinks it was completely unreasonable for them to have even tried the handle?!