To be fair, that's not much different from many outstations or small depots for drivers out and about during the day. I don't know how often Falmouth drivers go back to the depot there but it's not got a huge amount of facilities either.
Falmouth does have facilities for drivers at The Moor though, right near where the buses park. Do drivers for TfC at Penzance spend breaks in Morrison's?! Café isn't open but at least there's a loo and takeaway food!
In any case, with almost all ferries weather is a huge factor these days, with services cancelled almost at the drop of a hat (or, rather, the hat blowing off in the ever-present wind.)