I never previously had strong feelings about teachers holidays but would probably have said it was a nicer/easier than average job.
Then I started working as a school secretary 2 years ago. I'm at govt. maintained nursery school, staffed by a mixture of teachers and nursery nurses and they earn every second of their 'holiday' as do I and my other support staff colleagues.
There are very few people at my place of work who don't give additional time voluntarily to the running of the place and the welfare of the children, and invariably both teaching and TTO office staff come in during the hols (in fact there are two of us in the office who have just had our term-time only contracts changed because we were needing to come on anyway).
(BTW there is no guarantee that staff aren't there just because you can't see a light on - we are very conscious of our utilities costs and in areas where there are no kids always have lights off unless it's vital).
Because of the amount of stress involved in the job, there is a high incidence of staff sickness which needs to be covered, meaning other staff don't get their planning time so spend their own time on prep, learning journals etc.
As for INSET days - it's great fun. I have to manage mine (when I have to attend) and DD's (when she doesn't and are invariably different to mine). Meanwhile DH is at a private school and doesn't have any. They are for the most part really important, but if I'm honest (and especially as support staff) deathly boring!
And I know this is a proper petulant whinge, but there are downsides to not being able to pick and choose when you take your holidays no matter how long they are, not least the massive price hike that applies to the travel industry during the main school hols. We have had 1 'proper' holiday in the last 12 years because of the additional costs involved.