Many hosts would love to provide breakfasts but can’t due to local laws that require us to have commercial kitchens. Bear in mind too that for those of us in the USA (and possibly other places) we would be open to litigation if a guest had food poisoning - even if they contracted it at MacDonald’s and not at our rental.
When I had a traditional B & B in the UK I would ask guests beforehand if they had any special requirements (if they booked in advance, sometimes they just turned up on the doorstep with a suitcase). No-one ever had.
So they got cereal with milk, then a full English with bacon, sausage, eggs, grilled tomatoes, beans and fried bread and then toast and marmalade afterwards. Plus of course, unlimited tea and coffee. No-one ever complained or wanted anything different.
I well remember one American couple who put marmalade on their full English plate as though it was some sort of condiment or sauce. I really doubt it went well with bacon and eggs.