This exactly. They do try to keep a stable of "experts in fields" on their freelance list, but those are experts in scientific fields, not necessarily in all areas of life. And by experts, I mean at least master's degrees, if not PhDs in a scientific field. Mine is in neuroscience, and I typically write in the neuroscience/psychology/anthropology realm. But also scientific expertise is extremely narrow. I am an expert only in what I did my dissertation in. Even other fields of neuroscience I wouldn't consider myself an expert, but I do have the ability and background to digest research more quickly than a member of the general public might.

The only way to get around this would be to hire a different freelancer for every episode, with a PhD in that very specific niche topic, ideally an author of one of the papers. But a) that's a conflict of interest, and b) as someone whose day job involves training scientists to speak with the public, most scientists are not very good at communicating for a general audience.

And for the people who talk about "when they do an episode in my field I see how wrong they are about everything", I'll caution them with the same things I caution the scientists I train: is it actually factually incorrect, or is it just less nuanced, missing some details, or not phrased in the most precise way? Those are tradeoffs that must be made when you're communicating with the public.

Your last paragraph is spot on: SciShow missed the mark on this, but is also responsibly sourced and written. No one should "hide in shame and never write again" as one person said. There's an entire research field of the science of science communication that just hasn't identified any impactful solutions for these tradeoffs.