@Anxioys
If I go to a sandwich shop, they make it from scratch for me.
Yes, but the ingredients are highly likely to be processed crap.
Margarine will be,
As will salad cream/mayonnaise,
As will be the bread,
Meat slices will almost certainly be processed from a pack,
"Wet" fillings such as chicken & sweetcorn, or prawn/egg mayonnaise will be processed bought in bulk (there are numerous sandwich filling manufacturers),
Take a look in their waste bins behind the shop and you'll find large plastic containers bought in bulk from food processors/wholesalers, usually with long use by dates meaning lots of added salt/sugar and other preservatives.
You're probably only looking at lettuce, tomatoes, cucumber that will actually be "fresh" and unprocessed.
Obviously, "artisan" style sandwich shops may use more fresh/unprocessed ingredients, but you'll be paying through the nose for them.