"I get that teachers feel they are being penalised for parents' decisions."
For me, it's not like that. It's a bit more personal, in many ways, and it's about the children, not about me or the parents.
I see parents and schools as a partnership, who need to work together to ensure that the children in our mutual care make the best educational progress that they can. My part of the deal is to teach the children as well as I possibly can, to get to know them, to motivate them, to help them when they're stuck, to investigate any difficulties they have and to continually challenge them to learn new things. If I teach a bad lesson, if I ignore your child's needs, if I move them on too fast or too slowly, I'm letting down my side of the bargain, and that (pathetic, I know) saddens me.
Equally, I feel that parents who take children out of school on holiday 'because it doesn't matter', due to a want and not a need, are not quite keeping their side of the bargain, and (again pathetically, I'm sure) I feel that if I keep explaining that yes, it does have an impact, yes, it does affect the whole class too, more parents will understand this and choose not to, whatever the position on fines etc.