Not in a 'sheltered' flat - but our small block of 25 flats are occupied by a lot of much older people. Oldest is going to 104 this year, several in the mid-late 90's, and a large number in their 80's. All living independently, but 'buying in' any services they require (meals on wheels, cleaning, etc.).
When I moved here I was concerned about similar things as the OP. Worried as to what happened to rubbish, etc. We are a very large 'cupboard' on the ground floor, which contains (now) two large black bins for non-recyclable rubbish, and other bins for things like glass, paper, plastic, etc. The cttee here offer a service to anyone in the flats who is unable to take their rubbish bags down there, that we will collect it from outside their front doors the day before collection day. Nobody has yet taken us up on this. Equally, we say if the lid of the black bins are too heavy, for people just to leave their rubbish bags leaning against them (against never required).
We have security main entrances, with keys that cannot be cut without express permission from our management cttee. Those doors can be opened from inside each flat. Buzzer system outside. Food deliveries are brough right up to the front doors of each flat. (pre-covid right into kitchens).
Letter boxes for each flat is external at main entrance, with each flat owner having key to open their own letter box from inside the entrance hall. Same key opens them all, and Cttee members are always happy to 'look after' people's boxes when they are away from any time. Parcels, can be brought up to flats (provided the recipient is at home to let them in). Otherwise, they are left in entrance foyer.
Best way of finding out is to visit flats, and ASK all these questions. They may well, as we do, have a printed information sheet which covers all of these points.
However, as others have said - do watch out for some of the 'hidden' costs of these retirement/sheltered properties. They usually have an extremely high maintenance charge, often have a list of tradesmen who have to be used for any work being carried out in the flat, may well have strict rules as to WHAT work/alterations can be carried out AND often have a system where when wishing to sell that property has to be sold via that management company with them taking a percentage.
A normal flat can be just as secure and with the usage of either something like Alexa (if you have family or friends locally), or the necklet/bracelet with red button which enables you to call for help. Usually, larger flat, costs less. cheaper maintenance charge, etc. etc.
