Schools don't make decisions based on what will make parenting easier for you.
They make decisions based on risk assessments, and I'm glad we haven't followed France with a blanket approach. Different schools have radically different circumstances.
For example, DS1's comp now has half the classrooms air conditioned - the current head has made it her top priority for capital budgets. With Y11 and Y13 gone and a supply of portable aircon units, school is the best and safest place for them to be, even with going home in the hotter part of the day (fairly small catchment, no Tube or similar.)
Comp down the road was built about 20 years ago and is visually lovely with all its south-facing glass. It is also the equivalent of a greenhouse in this weather. No way to keep the students adequately safe, so they're closing at lunchtime.
DS2's primary has optional pickup from lunchtime, recognising that for many parents as well as small children, walking home in a slightly cooler part of the day is preferable and that classrooms with 30 kids are harder to keep comfortable than classrooms with 20. No aircon but lucky to have a playground with lots of shade and very little concrete, and good airflow to classrooms. After school club is open but they're not charging if parents choose to keep kids home instead.
It's not a school's job to take "some of our parents struggle to be firm and realistic with their children" into account when making decisions about what's safest for the people working and learning at the school.