system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are the reasons for scrum penalties in the Rugby World Cup?

It seems Iike the majority of scrums result in a penalty.  I can't see to identify what team has done what incorrectly.  It looks like a lottery to me,  with a penalty blown to either team for no logical reason.  

What should I look out for when watching scrums,  and what are the most frequently broken rules?
gpt
Watch for players standing up early, mainly second row. Or guys in the front row dropping their shoulders towards the ground. This is a sign they are about to collapse.

If one team is stronger, they will push their oppenents backwards and either win the ball or cause the other teams scrum to collapse. If you are the team who does not have the ball at the start of the scrum, winning a penalty is just as good as winning the scrum.

Another thing to look as is the binds between players, particularly numbers 6 & 7 on the edges of the scrum, they are meant to have their whole arm bound to their teammate, not just their hand.

There are also rules around wheeling (rotating) the scrum, if the ref thinks you are trying to do this intentionally, he will give a penalty.