The way UPS told me once is it's the drivers discretion whether to leave a package at someones door or not. If the driver knows theft isn't prevelant in your area then most likely they will leave it. UPS, DHL, etc. all leave packages at my front door without signatures unless i happen to be there of course. my front door is somewhat hidden by landscaping so unless you walk up to my door you won't see anything sitting there.
good luck getting this fixed!! I have a complaint for thiefs and our, as a consumer/customer, recourse of stolen phones.