Are supermarkets any good?

When I used to lecturer at an agricultural college many of my students would spend evenings, weekends and holidays doing farm work in order to secure extra beer tokens.

So it was noticeable that when a large Tesco’s opened nearby how many of them migrated to stacking shelves instead of getting dirty down on the farm.

When I asked them why, the answer was always the same; easy money.

It was physically easy, no one hassled them, they could come and go as the pleased, they didn't get wet, cold, filthy dirty and the pay was good.

The work was hardly satisfying and was never going to be a long term career option because it didn't involve tractors but it was very much in contrast to the jobs they had been used to doing so much that they thought it was an absolute breeze.

Now we all know that ag students are a breed apart and thrive in a working environment that would make lesser mortals run home to mummy in tears but even so does this mean that the big supermarkets are inefficient? 

I get the feeling that supermarkets set the bar quite low when expecting output from their shelf-stacker's and if this is the case does it permeate through the rest of the business.

Are farmers being penalised for inefficiencies in supermarkets?