As David pointed out: he gets bed & board free; he has a business base for free, including internet access; he has full run of all the farm's workshops including welding gear etc.
Basically, his business has no overheads.
Besides, isn't that what family do?
Josh is their 19 year old child! He's trying to forge a career that won't leave him dependant on Brookfield. He hasn't had any of the support that Pip's had! Sure, family help out, but not to the detriment of their own career. It's the inequality that bothers me. He sorted out the silaging by paying Ed. Why is that a problem for David?
How is Josh supposed to generate an income if his family have first dibs on his time as and when it suits them? And let's face it, they only need him now because of the mess that Pip caused.