I totally disagree with fines being imposed by schools. I don't approve of any form of control that differentiates between those with money and those without - I feel the same about charging old cars to enter city centres or congestion charges that allow the better off freedom of movement denied to the poor. Also, fines should be imposed for criminal activity at the discretion of the courts, not for saving money on holidays at the discretion of a school Head. I don't see why 'educational' holidays should be exempt either. I agree that this attitude is simply snobbery. Either there is a rule or there isn't, and it should apply whether you are tramping round ancient ruins or playing bingo in Blackpool.
We always had family holidays in school holidays, as I was marking or attending Exam Boards in term time, and the only time I could realistically have taken leave out of the school holiday period would have been in September, which would have meant the children missing the start of term and getting to know new teachers, timetables etc, so it didn't happen. We always managed a holiday, but it was sometimes a struggle for my husband to get time off in August as his colleagues had children too, and they all wanted time off in school holidays.
When I was a child there were holiday forms that parents filled in to get authorised absence for 2 weeks of the year. I always thought it was very exotic when friends got them, but never got to ask for one as my parents didn't believe in taking holidays in term time and my father could take leave when he wanted (my mum didn't work). AFAIK, the children who did go away didn't suffer though.