memes

There’s also no good logic or intuition about what technology does or doesn’t work. An electric kettle won’t work but a whole ass car will?

Sometimes the answer could be "hey, we don't know everything there is to know about our magic. Sure would be nice to know why some kinds of tech are more affected than others, but our level of understanding isn't there yet."

Because it’s a cop out. You’re not putting any thought into how your systems would interact with modern tech. Even if you really need a modern setting with no technology, at least be imaginative with why that happens and maybe let that reason affect your setting in some other ways as well.

But maybe it doesn't matter to the story. HP isn't a role playing game (there probably is one now, but at the time it was created). There's all kinds of things we didn't and/or don't fully understand about our real world. If they had defined the "rules" of HP magic in a way that satisfies the concern in your example, I don't see how it would have impacted the story much. If anything it might have killed some of the fantastical bits of the storytelling. It's not that sort of magic - I'd call it a "soft-ish" magic system if we're going to define things that way. Muggle tech is unreliable around it - and Weasley had apparently done some kind of tinkering to kind of get the car to work because he was a geek like that. Works for me.

I get your points, I'm not trying to say you are wrong, I'm just saying the importance of that sort of detail can be kind of subjective. What I enjoy about the HP universe isn't the slightest bit ruffled by that little bit of ambiguity. In a universe where the author really tried to keep things real feeling, I probably would be bothered, but there is so much more to criticize about HP before you get to muggle tech for someone who wants magical realism that it just seems like a weird stopping point to me.

Maybe you just prefer a hard magic system which is totally valid, but IMO that's a matter of personal preference, not "correctness" if that makes any sense.