How often do you see homes with high walls topped with spikes, an electric fence, or razor wire?
You will not find it in most of Vienna, as most of it is ~4 story buildings.
For actual houses, can't think of a case either, but admittedly I've not really paid attention.
Amazon parcels get left with a neighbor if not home, post office either returns to post office for pick-up, or if small enough there's an extra box by the mail where you can use the bar code of the letter they drop in your post box to open it and collect your parcel.
In some buildings it gets left at the door, my building not really since always someone at home in it, lots of people.
In village by my grandfather, enough people leave parcels at the door, not an issue.
You need to remember minimum wage is 1500 EUR / R25k pm, there's also social housing etc., so you don't really have "poor" people if you can manage to land a job. Issue is more migrants that are looking for a job, but again, haven't had any issue with crime and I've seen one case of someone getting something stolen out of a handbag in the 8 months I've been here, and I take public transit multiple times a day. Cape Town, while I was in uni, I heard of someone getting mugged at least once a week or so, thanks to train station and district 6.