Firstly, Elegran, what a brilliant analogy! The cupcakes comparison very succinctly reveals how a system which is set up to educate children simultaneously, is, by parents seceding from group education, forcing educationalists to provide private, individual tuition without contributing the resources to do so.
There are arguments to be had on both sides of the case, on the one hand children benefit from family time and often learn a lot on some sorts of holidays and on the other hand children might well miss essential schooling by being taken away in term time.
As a former teacher I have seen both extremes. One middle class couple took their children away on a yacht for a year and the children wrote up their experiences in a diary supervised by the well informed parents who were natural educators. Another child went on a week's break in the important run-up to the SATs and came back not even knowing the country she had been to as she'd spent a week by a pool in a hotel. And there are countless gradations in between.
What I can say without any doubt is that given the National Curriculum and the exam system any absence will result in gaps some of which might be crucial in understanding a whole topic or a half term's work.
The problem I see is this. That the parents and the children benefit from the holiday but the teachers are unfairly penalised for it as they are now quite punitively judged on their pupils' progress in a way which wasn't the case in the past.
A holiday which results in a 'borderline child' gaining a D grade at GCSE instead of a C grade affects the school's results and the teacher whose pupil 'slipped' will be targeted adversely. Pupils are now meant to make 'two levels of progress' between year seven entry and GCSE and this is hard enough without any absences because achieving level four at Key Stage Two SATs is not really sufficient to make a C grade without hard and focussed work.
My solution would be to make term-time holidays on a 'at your own risk' basis whereby parents would sign a form to excuse the school from having to reach the targets set for their child and the child would be taken off the school league table statistics.
This will never happen in a million years because the whole point of the attendance drive was to make teachers responsible for that which should be the responsibility of parents: their children's progress in school. It is not 'democratic' and 'equal' to tell parents the truth, i.e., that term time absence damages their child's education and that they should put that first for a few years while the children are in school.
However, if parents don't view education as an 'exam factory' and are relaxed about results why should they not spend a happy time with their children? Philip Larkin writes about 'that toad, work' squatting on our lives. However, he does conclude in the poem that, however much we dislike it, the alternatives are worse. I think that the important things are that parents make their decisions with their eyes open (and absence does damage learning, for sure) and that teachers are not blamed for what parents choose to do.