@spendius,
Fernand Braudel said that 30 or 40% of economic activity consists of direct exchanges of services (ahem!), moonlighting, homeworking and odd jobbing and this whole range of activity lies outside official accounting procedures.
He distinguishes between "material civilisation" (the shadowy zone) and "economic civilisation". The former being difficult to see because of lack of documentation and complexity. But the shadow zone is basic economic activity which goes on everywhere and the volume of which is "truly fantastic".
It is the "informal other half of economic activity, the world of self sufficiency and barter of goods and services within a very small radius".
The historian, the economic expert, looks only in one direction, presumably for simplicity's sake, the easy way of being an expert, and it is the direction of the economic civilisation to which his eyes so readily turn. There he sees the formal hierarchies which manipulate markets and engage in "circuits and calculations that the ordinary people know nothing of". (see Pareto's circulating elites.)
Without this Shadow Zone the structures of the Economic Civilisation are not possible. It is only the records of the EC that show up in documents.
Ignoring the Shadow Zone, the non-working mother, the unpaid carer, the informal sexual trade, the trade in drugs, is not really discussing "the economy" at all. It is taking a grossly simplified view of life and hence it is attracted to published statistics for ease of understanding.
Almost every thread I go on betrays a determination to avoid complexity, subtlety, nuance and informality. Keep it simple eh? Let the official statistics tell you what to think.