Very sad. I once saw a volvo estate with bikes on a roofrack drive into the height barrier on car park in the centre of Benodet - the, English, driver had obviously forgotten about the bikes.
A practical tip I once heard of being used by a breakdown operative who attended a vehicles stuck under a height barrier was to let down the tyres. The few extra inches gained enabled the motorhome driver in that case to reverse out.
To try to avoid problems In the important documents folder we carry in the car, when on holiday, the front page is a list of all the car and caravans' dimenions (HxwxL), weights and tyre pressures so they are instantly to hand if there is any concerns.
Tim