Lack of monetization is fully taken into account already - the number given for income is not the sum of monetary transactions per individual but the income per

Lack of monetization is fully taken into account already - the number given for income is not the sum of monetary transactions per individual but the income per individual however obtained including barter, food grown+consumed by oneself, self-built house, etc. Even in the late middle ages monetary transactions were not the common case so it would be absurd to conflate monetary transactions with average income.