With regards Signatures ... yes, during Covid we were Signing on behalf of a customer but we would verify the person and type that in, not all posties do things the same, Sometimes if large letter signed for is used (which i do for sligthly valuable items) the postman has to try and get the occupant attention but when they dont answer the temptation to post it via letterbox is there.
With regards 'recorded' delivery, some 80s thing I think that is.... lol
With regards the lost items, you have to put a claim in and hope for the best. Tracking should give you an indication where it broke down, for a postie to say that we 'dumped' a parcel as the guy above said, do you think we would get called into the office to explain a tracked item dumped? they do like succesful figures the depos. Ask customer services for the GPS and the photos. All tracked is tracked, simple as, should get a scan each day.