Sorry pointy, I really didn't mean to be patronising. I had read your 'that is not the case in Scotland' as a question about why it wasn't the case in Scotland, the answer being devolution of education. That obviously wasn't what you meant, apologies.
To reply to the 'why do they [schools) put on trips' I can only describe my own experience. I teach in a small rural school, with a substantial minority of children with very very little life experience who have never been more than a few miles from the village, never seen the sea, never been to the nearest city 10 miles away etc. The National Curriculum suggests that we teach these children things like the Tudors or Victorians or about coasts. Yes, we can do a lot with multimedia information sources, artefact loan etc but at the end of the day as educators we want the children to have some 'actual experiences' of the type only we as schools are ever likely to deliver - to visit a castle, a Tudor house, a place of worship for another religion, a museum recreating the Victorian period etc. As we are rural, none of those things are on our doorstep, so we have trips, and trips mean coaches which are expensive.
Also with respect to swimming - again, as we are rural, swimming means a coach journey. Money to deliver swimming IS in the school budget - but the money for the coach isn't. Is it right to use school or PTA money to pay for the coach (we have an active PTA, but again the ability of parents and community to give via that route is relatively limited especially in the current economic climate) for the 2 classes who go swimming? Or for the playground which will benefit everyone - and it IS an either/or?