I think the fact that the majority of teachers do not support fines is a very important point.
Teachers have nothing to gain by not supporting fines (unlike headteachers who apparently gain a load of time by not having to make decisions on whether or not to allow holidays).
They cannot take their own children out during term time as they are working so wouldn't benefit from that.
If you believe that children being off only creates an extra workload for teachers then why wouldn't they be all for fines? God knows the workload is heavy enough already.
Performance management means that many teacher's pay increments are based on how their class performs. If holidays affect this why would every single teacher not support fines?
Why would they look at a correlation between absence and educational achievement and still not support fines?
I believe it is because teachers have experience of hundreds of children, they know what affects learning and mostly believe that family time is incredibly important to a child's wellbeing and success.
They also know that unless a child is a persistent absentee then a week here or there in non-exam years is not going to make a big difference to their educational attainment.