“Let’s put the secret entrance to our magical train platform right smack in the middle of London’s busiest train station! Make sure the [slur] don’t see you!”
“Let’s use owls, some of the slowest birds ever, as delivery system.”
"The bank is just actual vaults with piles of money and being run by Jewish caricatures."
“Let’s put our teleportation system in a fireplace, so you can risk getting grievously burned if something goes wrong and you carry ash everywhere.”
“Forget electricity, we’ll light up our ancient castle with floating candles that can drip wax everywhere.”
“Let’s have movie stair cases with no safety mesure in our school for children.”
“Let’s teach children how to make mind altering potions!”
“Let’s give a time travel device to a girl so she can get extra credits.”
“Let’s put all the supremacists jerks into one house and all the reckless holier-than-thou types in another one.”
“Here’s a game where children hit each other with sticks while flying 20 feets in the air and the points don’t matter because Potter keeps catching a friggin’ gold ball.”
I don't actually want to defend Rowling's world building. Because it is rubbish. But I have to give passes to a couple of things on your list.
Putting the secret entrance in the middle of Kings Cross makes sense from a comedic perspective and a "the magical world is right alongside us" perspective. RE. moving staircases, which aren't even close to the worst things that have been put in Hogwarts, adult indifference to children and their safety is a staple of kids' literature. So I give this a pass too.
But if my add a few more WTF? ideas to your list:
Polyjuice potion. So simple even kids can make it. Bright kids. Well, Hermione, later Malfoy. But presumably many adults. Yet the government has no defences against its use, not even for the gorram Ministry building.
Invisibility has the same problem. Yes, we are told that invisibility cloaks are hard to make and rarely last long. But that doesn't excuse the Ministry, or indeed any adult wizard, from failing to suspect/prepare against their use.
The good guys (sic) casual indifference to slavery. And indeed the wizard's marginalisation of all the magical peoples. It is introduced as a thing, and we are given several examples of it, and nothing ever comes of it.
I know you've already mentioned quidditch but I would just like to mention it again cos it's just so awful.