It's worth pointing out that Facebook tried the human curation thing and were accused of bias.

That's fine: They should own that, then. "We're Facebook and these are our values -- we trust the BBC and do not trust InfoWars.com"

These big tech companies are trying to be all things to all people, and they want to pretend that using algorithms means they're free from bias. It's just a different, more opaque bias encoded in the algorithms.

But users are inclined to trust it because it comes "from the computer". It's a Garbage In, Gospel Out situation.

You mean like every human-curated news source since the beginning of time?

Human curators are biased. Google company culture is left-leaning as a whole, so you'd expect to see that same bias in any curated content they provide.