When is a door not a door?

I completely understand that the new face-covering legislation is to allow those members of our society who have been instructed to shield at home for the last four months to get out to the shops for themselves without the fear of coming into close proximity to a stranger with an infectious cough.
I also understand that the rules are different in pubs and restaurants because it is not possible to enjoy what these venues have to offer while covering one's face and anyone worried about coming into contact with someone with an infectious cough can easily avoid such places.
But the whole nonsense about eating-in at a take-away has become a joke. It could have been simple; if you are eating in you must not approach the counter but instead you must sit at a table without covering your face and a member of staff who will wear a face covering will serve you at your table. But if you are eating out you must wear a face covering, approach the counter, collect your food and leave.
As far as I can tell the Govt. instructions missed out the crucial bit about being served at your table. They could have made it even simpler by saying that providers of prepared food can offer either a sit-in, or a take-out, but not both.

I was struck by the complexities of the new rules in Chatham High Street today. People walking along the street in the open air were not necessarily wearing masks but they put them on when entering shops. Good.

And then I entered the enclosed mall. I assumed that as an enclosed shopping space I should keep my nose and mouth covered, but plenty of people were treating it in exactly the same way as the street outside and adding face-coverings only when they entered a shop.

But what about Greggs and Subway who have actual shops inside the mall but who have ouside seating outside their shops but inside the mall?

And what about the “market stalls” inside the mall? Are they open air? Are they shops? If I buy a home-made treat and eat it wandering around inside the mall am I eating in or have I taken it away?