>In few countries however such kind of "productivity" is considered a kind of (self) slavery and it's not really accepted. For instance in Swiss it not common at all eat in your workplace no matter the provenance of food because we do not live for work but the contrary. In French is common only for low-paid labors, mostly young at career start etc.

This is fascinating and very interesting from a radical point of view. A while ago there was a thread on HN about if it would be bad for a workplace to have bunks and a kitchen such that employees can sleep there. To me the whole idea felt incredibly dystopian. In the end, though, some authors have observed a kind of cultural shift, in which we are no longer told what to do at work, but rather the workplace tries to align our desire to theirs, the analogy Frédéric Lordon[0] uses is that desires can be expressed as vectors, and the modern workplace, lacking the old methods to make us work (because they are culturally inappropriate, or illegal) must use such a method which seems a whole lot less pernicious at face value.

It's not only the time to make the lunch which counts as unpaid labour, it's also the time and expense to travel to work (and according to some stories on HN this can get to absurd levels) and due to the phenomena I mentioned a lot of time spent around work doing non-work activities (though this is more common if there is a "workplace culture").

[0] "Willing Slaves of Capital: Spinoza and Marx on Desire"