The Rules of Death In Blackbirds by Chuck Wendig | Spoilers!

Yesterday, I've talked to you about the book Blackbirds, but I had to make an extra post just to discuss the concept of death in it - because I still don't fully understand it. 

You see, Miriam sees how you're going to die. Throughout the book she sees countless future deaths, always insisting they can't be changed because of one incident where she took the active approach (instead of just telling people that they're going to die which, let's be honest, who's going to believe the crazy chick telling them that in seven years and three days they're going to be run over by a car?) and failed spectacularly.

Since that moment, she firmly believes that death can't be stopped, and she's just a spectator of it. She stops trying, and even starts to profit off the deaths she sees.

But at the end of the novel, she discovers that to stop death SPOILERS!
 one needs to give him another life in exchange.

Now this makes no sense to me.

Miriam killed Hairless Fucker (Miriam's pet name for him. Actually easier to say than his real name) to save Luis's life. This supposedly evens the scales and it's why it was allowed - a life for a life and all that shizzles.

BUT THIS MAKES NO SENSE.

In Miriam's vision of HF's death, she saw him seven years into the future, and he went down killing two other people with him (in a very grotesque and cartoonist way, too). So by killing him, Miriam has thwarted not just Luis's death - but at least other two deaths. Probably more because HF is a serial killer and a drug dealer (so he's got od's on his conscious as well).

EVER HEARD OF THE BUTTERFLY EFFECT? 

By killing HF, she's caused a massive disturbance in fate's plans. There is no way in hell the balance is kept after that. Now, this is okay. Life isn't fair, so why should death be? It would actually be far more realistic if this is the case. Like how often in books, a character saves one person only to lose three.

LIFE ISN'T FAIR AND DEATH ISN'T FAIR AND YOU DON'T HAVE TO EXCUSE IT!

But this book trying to "explain" this rule because of the balance is complete BS. Now, either we find out more about this and how it's not this straightforward as the ending would like you to believe, or I would be sourly disappointed.

Aside for that, I just didn't understand what made Miriam so certain she couldn't stop death. There is a scene in the book where a young man is killed by a fall down the stairs. It would have been very easy to prevent. All you had to do was go with him. Or tell him to watch his steps down the stairs as he already known her ability. Say something.

The book failed spectacularly  to convince me Miriam couldn't have stopped countless of deaths from happening. Just because she failed with one kid, she gives up. And then plays the "it is what it is" card to cop-out of trying again.

Have you read this book? What is your take on the fate/death system in this world?