Ohhh no, we definitely have a theft problem around here. I've not personally experienced packages disappearing like that —— mostly due to making sure I'm home every time XD —— but in my town's Facebook community group there have been several complaints of package theft.
Things that are sent via registered post require a signature to retrieve though, so if no one's home it goes to the post office instead of on the doorstep. Non-registered things are left on the doorstep. I try to register everything I get delivered which is safer! 😅