>Both Spotify and Apple Music algos have no idea about music mood vs time of the day vs activity.

You say that, but I attended a conference with Spotify- they are specifically working on that problem now.

If they're working on it then the point still stands that they don't currently have it as part of their product.

Time of day aware recommendations is something YouTube seems to have had for years. It always knows what to give me up top based on if I'm sitting down for dinner or lunch or if I'm looking for an audiobook for bed etc

Isn't that more just you thing though?

Why isn't late evening before sleep good for heavy metal? I listen to the same music I listen to all day before sleep if I had music on.

The music I listen too doesn't change no matter where I am or the time of the day.

What that really means is that they either:

1) aren't doing the sensor fusion we all think they are, out of inability to access the data.

2) the models (and therefore modelers) aren't good enough to use the data they have correctly.

Or 3) they run loads of A/B experiments to optimize engagement or some target metric and they've reached a local minima and are unable to escape it without a lot of political will or Product Managers willing to stick their necks out.

Google Play music had that feature. I really miss it.