The "lazy peasant" is a slander of the leisured classes: pre-modern farmers stopped short of maximum effort because their priorities were not served by more of it.

Ancient and military historian specialising in the economy…

This isn’t because they are ‘lazy’ – the ‘lazy peasant’ (or poor worker generally) is a standard hypocrisy of the literature of the leisured aristocratic class towards poor farmers, today and in the past – but because they have priorities which are simply not served by labor maximization.