Why didn't Alexander-Arnold get a red card?

Why didn't Alexander-Arnold get a red card?
by spade (2019-05-05 00:15:13)
Edited on 2019-05-05 00:16:10

In reply to: Liverpool escapes * posted by dwjm3

I haven't understood this for a while in similar circumstances. For those that didn't see:
On the first Newcastle goal Alexander-Arnold handles the ball with his elbow off the line to prevent a goal, and the ball falls to a Newcastle player who immediately scores. Sure, that may not have been deliberate, but clearly would have been a penalty had the advantage not been played and scored a goal.

My question is, why are red cards not awarded just because a goal is score, as it's a foul worthy of a red card, a handball on the line? And if a studs up, violent tackle happened in the box (a la Foyth, ouch that hurts to remember that) and still a goal was scored on advantage, I would think a red card should still be handed out, right? But maybe not?

So why would an egregious handball also worth of a red card not result in a foul? Or at least a yellow? It's cheating isn't it? I haven't understood this for a while, so I welcome those with more experience to explain it.

Still, for the sake of this Liverpool-Man City title race, I guess I'm glad Liverpool manged to pull this out.