Teacher here, so have seen the other side of this. The sad truth is that families are struggling at present, but schools are too; there is often real pressure (both from some parents, and Ofsted/the government) to do more in the way of 'experiential learning' - trips, visits etc - but schools simply do not have the resources for this. In my experience, we're often damned if we do and damned if we don't - many parents want this kind of interactive learning for their children; many children learn best by getting out of the classroom and doing, but we're also painfully aware that an increasing number of families struggle to afford these 'extras'.
In my last school, many of the parents had found out that the previous year group had visited the seaside as part of their topic, and were reguarly asking us to arrange the same trip for their children. We phoned around every coach company in the area, and the lowest quote they gave us would require us to request £15 per child just for the coach. We didn't charge parents the full amount - the school met some of the costs - but we did have to ask for around £10, just to get the children to the seaside and back. Similarly, the local council music service once tried to charge us £400 for an hour-long demonstration of some Spanish/Latin American music as part of the school's Spanish Day. We told them where to go and managed to cobble something together ourselves, but it highlights how many of these educational services know they're on to a good thing and overcharge massively.
Another school I taught in tried to cut costs by using public transport for trips rather than coaches. Taking the train/Tube to a London museum, enabled us to reduce the cost to parents from £16 to £3. However, a significant minority of parents were so aghast at the prospect of their children taking the 'dangerous' train (even with a 1:3 adult:child ratio) that they refused to give permission for them to go. They would rather pay the full £16 for what they saw as the added peace of mind.
Lastly, as someone who has frequently had to accompany classes to school swimming lessons, I agree with the OP that these are often a complete waste of time; the children who can already swim end up bored, and those who can't rarely learn anything because the teaching groups are so big and the teachers so uninterested. I've intervened a couple of times because the pool staff were standing around chatting instead of actually teaching, and was given short shrift - they know that schools are compelled to use their services as part of the National Curriculum. Most schools I've taught in have allocated funds for swimming themselves, but nonetheless if I were the OP I would raise this matter with the school.