Why Is This Not A Draw?

This is an interesting situation indeed. White just blundered their Queen (their last remaining decisive piece) and Black has no valid moves to make other than capturing it -- which is automatically a draw.

However black failed to do so "in time". In other words, even if the next move is leading to a forced draw, you should consider that Black still has the option to "Resign" the game instead of making their next move. There are 2 valid ways for it: declaration or letting time run out.

In this case, the system can't possibly decide which maneuver Black intended to take. Therefore, the only logical conclusion is to give White the victory.

Everybody seems to be missing that after the last move black has no other legal move than taking the queen, wich results in K vs K and a technical draw. Probably the developers didn´t think about this situation, but to be fair, it will just about never occur in a proper game so debating wether or not this should be a draw has no meaning whatsoever.

I could see this happening in an ultrabullet game.
I don't think the 'black can resign' argument really applies, because lichess lets you resign in any position that it is impossible to lose. If the system doesn't give white the win when black loses on time and white has insufficient material (it is considered a draw in that case) despite the fact that black can still resign, then why should it do so here?

In your last question, the conditions for a draw are met when a side remains with insufficient material (in which no checkmating opportunities are present). No further moves are allowed (I'm assuming, don't quote me on it) and the game instantly ends at that point. Just like in a K v K situation.

However in your main example, the conditions are not met "yet" for a draw. That's the difference.

The time runs out before Black makes their move. There's the possibility of uncertainty involved. We don't know what black will do next. I'm only saying this to open a different window on the matter. Otherwise, Black just lost on time before they could officially meet the conditions for a draw.

That's the whole story.

It is only a draw if someone has two queens and the opponent has only a king but the player with two queens clock runs down.

According to FIDE it would be immediately draw. It doesn't matter whether it is a sequence of 1 or n consecutive moves which leads to a "dead" position.

It is not checked here because the real fortresses are hard to detect. This one would be easy, but ... consistency.

This has been discussed many times here.

This is also a "win" in case white times out, although there's is no winning possibilty for the other side.

Probably a draw, because it is a classic 'timeout vs. insufficient material' situation. Black can win and white cannot, but black has no time.