Deliveries left unsecured on a doorstop is a common practice in the US, typically found in low-crime residential areas. It was by no means invented by Amazon -- it's been a thing for a long time.
But if you live in a rural area, things are completely different. Which from my understanding is the same as EU for the most part.
Over literally thousands of deliveries during that time, the number that have disappeared mysteriously is under 1%. In fact, more have not been delivered at all (i.e., fraud on the part of the delivery person) than have been stolen.
https://www.nytimes.com/2019/12/02/nyregion/online-shopping-...
So, it's pretty much priced into their margins already.