This to me is quite a serious problem. Okay, so some hosts leave their properties unlocked. I find that strange, but then I live in a big city where no one leaves their front doors unlocked.
My front door locks automatically when you close it but people used to leave it open all the time. I now really stress to them on check in that they must close it. Seems to have worked.
However, getting them to shut and lock the back doors before they leave seems to be a problem. I raelly make a point of this as well, but many guests still leave them open. Doesn't seem to matter how clearly I explain it to them.
I don't understand it at all. Surely they don't do this in their own homes.
@Mike43, I agree you need to put your foot down. Explain politely but firmly to the guest the seriousness of your request and why you cannot continute to put up with this risk. Tell them it's nothing personal, but for the reasons you just explained, you will have to terminate their stay if they don't start locking the door.
Ideally, you should make sure you back this up in writing on the Airbnb messaging system and if you think the guest is going to be unreasonable about it, it might be a good idea to alert Airbnb CS about it, explaining that the guest won't comply with this house rule and it's putting you and your home at risk. I think it totally depends on how sympathetic the CS you speak to is towards you, but I've had an experience with guests who wouldn't listen to me about following house rules and the CS rep called the guests and told them they had to or they would be asked to leave. After that, the guests took it seriously.