i am always perplexed by the overt or covert niggles at teachers and their hours. Particularly so as I've also read where it's apparent that the OP has a flexible time schedule and some helpful benefits.
I suppose we could trot out the old chestnut that I have been using since I became a teacher many years ago. "If it's so good, please join us. "
Several posters have answered the question posed by the OP on this thread and those answers all apply, dependent upon the school. Some finish early to stagger the finish times with other schools in the area. Some finish early to allow for prizegiving. Some finish early because they are preparing for a summer deep clean. Some finish early because.......and so on.
Every school I've ever taught in will have informed the transport providers of the different time, so buses, taxis etc, will be available to take the children home in the usual way. If it's primary, presumably the person who usually collects the child will do so- parent, grandparent, child minder.
I always spent the first week of the holidays in school doing paperwork and preparation. I would also be in school at least one or two days for the rest of the time, unless away on holiday.
There are threads about people desperate for their children to be at home. There are others dreading the holidays. Whatever schools do, it's wrong for someone.