I cook everything myself. Basic ingredients are cheap, so I don't need to be careful. This budget includes lots of wine and cheese. No compromises there.
Basic ingredients are cheap as long as we ignore quality and where I live, you're not getting any good quality wine and cheese in your 5 Euros a day.
Cheap supermarket budget brands full of chemicals, hormones and preservatives? Yes. Quality stuff? No.
As for diet - A typical day would like this.
Breakfast.
(them) Home made pancakes for breakfast with a drizzle of honey. (me) Muesli.
Lunch, Salad Wrap/veggie heavy (other half is vegetarian) or KaposztáS TéSzta (cabbage/noodles).
Evening Meal - Spaghetti Carbonara or Tuna Steaks/veggies.
My other half loves cooking (she's hungarian) and it's completely the norm that for her/where she is from to just do everything from scratch.
Lots of fresh seasonal veggies, lots of soups, noodles, pasta etc - it's a good diet tbh and seems to suit my health issues.
This is in the EU, regulation basically prevents excesses like that in most cases.
Furthermore, price doesn’t have to be a predictor of quality. E.g. LIDL/Aldi (budget chains) commonly win awards for best vegetables.
I used to spend ~150-200 on food per month when I was living by myself and wasn’t strictly managing it for low cost. Now with a family of 3, we spend 300-400€ a month on groceries (incl bread and meat) and are never holding back on anything because of price.
So, 5€ per day doesn’t sound unreasonable even in the Netherlands. Note: we eat vegetarian 5 out of 7 days, without that we’d probably spend 100-150 more.
Edit: I get that this doesn’t work everywhere. When I lived in the US (NYC) and tried to cook my own meals I couldn’t believe 1) how few supermarkets there were and 2) how high prices for basic food were. Eating out was basically cheaper :/
During this season it’s also soup time. Our favorite is butternut two oignons a bit of butter and cream or coco milk. Super cheap. Makes 2 to 4 servings depending on dilution and veggie size. Add 1€ for bread (for 2). And bit of cheese and / or fruit.