She murdered a sleeping man, stole his money and belongings and took them to her pimp.
She was 16, previously raped by that sleeping man and then she killed him and stole his stuff and took it to someone who forced her into sexual slavery and kept most of what she earned for himself. I assume she was physically afraid of him, and subject to serious abuse beyond the child-slavery and sexual exploitation, because this is real life.
There's no reason to look for simplicity where none exists. Everything about this is just horrifying - and there's also no need to assume that she is innocent. The imbalance being suggested is the sentencing and lack of compassion for what are the kind of extenuating circumstances that would already have destroyed the life, will and agency of anyone posting here.
And that's before you discuss what the benefit to Tennessee is to have her locked up for her whole life with no chance of redemption or moral improvement or meaningful education. It's complicated. She's guilty, this addresses what many considered a reflexive and politically motivated penalty, it doesn't absolve her of her guilt or responsibility but it does contend that the latter was diminished.
If your daughter was kidnapped, beaten, raped and forced into this kind of life, and then did the exact same things she did - even if she subsequently enjoyed it (which is a stretch I am adding for the empathy challenged right and wrong folks), you'd fight to free her, let alone get her sentence reduced. That's a useful perspective to apply here.
And her life previous to this was worse than the life of our imaginary daughter in the thought experiment, assuming we're all typing from at least basic comfort.
