How can you say that?
Do you think that they oppose it just because it was a Tory government who announced it? Labour agree with the government, yet the union is still opposing it.
It's presumption on your part to think that it's an auto-response.
About 300 open or in the pipeline, apparently.
https://www.gov.uk/government/news/more-than-100-free-schools-applications-approved
That doesn't include previously-opened academies and independent schools, of course.
It will be rejected because it's a bad idea - irrespective of who it's from.
If it was a good idea, I'm sure we'd have heard more about it before. There may be benefits to altering the school term times, but if you really believe changing them will be beneficial in the way you suggest, why...
Because they see it as a bad idea. Just because it may not directly affect teachers (though it will affect teachers who are also parents), it doesn't mean they can't raise the point.
The reaction is actually quite reasonable to such a poorly thought-out idea.
No-one was pushing for this idea...
Because teachers won't be that concerned over the change - it's not them who will 'suffer', at least not in their capacity as a teacher.
It will be families with, for example, children at different schools.
My better half can set her school terms for (within reason) whenever she likes.
So she sets them to co-incide with the same school terms as Brighton & Hove LEA.