"I often book the late afternoon ferry, arrive in time for the mid-afternoon crossing and am welcomed on board, at no extra charge, with a smile."
Ditto, but I do book a semi-flex fare to give me a time margin especially with a long road journey ... and the possibility of 'pedestrians in the road' on the Calais approach!
I too wish that this sort of flexibility could apply to flights to popular destinations with frequent daily rotations, but I suppose this would cause chaos (and potential overbooking!) at check in, or even worse at the gate for those who don't have to check in anything!!!