Because she WAS a good little girl. She was a sweetie. And because she really wanted Mommy's love but knew in her heart that it wasn't there.
It's not.
I really, really doubt Caylee was ever locked in the trunk until the day she was killed. I doubt she was ever abused in any conventional manner until casey murdered her. People find it hard to fathom that a person who generally took good care of her child could kill that child. People assume that because she was capable of murdering her baby, she must have otherwise abused her.
But I think it is very possible for someone not to love their child yet still basically take care of them and not abuse them or neglect them in a conventional sense. I think it is possible for someone to plan to kill their kid but have been a decent parent up to that point, or at least a passable one. Like Susan Smith. Like Darlie Routier. Like Chris Coleman. Like countless others.
I don't think Caylee was locked in the trunk because I have filled in most of the blanks as to where casey and Caylee were during 2008. It seems that casey at first left her child with her parents at night a lot, and then with the Grunds and I think it was Kristina, during the day. Then, Kristina said, "You're not working, no more." And then the Grunds also stopped the free childcare. After that, she seemed to be carting her child around with her a lot more often during the day, albeit grudgingly, as can be seen in the photos at the Lake Vaj house (I think it was).
At night, she continued to utilize her parents until they got wise to her tricks. At that point, CA started demanding proof of employment before she would sit for Caylee at night. And often, it seems, she gave CA the proof that was required, or at least sufficient proof for CA.
Of course, CA began to really uncover the truth about casey's employment status and really started making it difficult for casey to be free. Then, casey found Ricardo. He allowed the baby to spend the night, in his bed. So, casey continued to be free to some degree for awhile and Caylee stayed safe for the moment.
It started screeching to a halt when she hooked onto Tony. He didn't want a baby in his bed. And this was at the same time CA was clamping down harder. The timeline during that time period does not show a night when Caylee was unaccounted for by a third party. But, once casey found it harder and harder to go out and have a place for Caylee to be, she killed her. I think if Tony had been cool with having the baby in his bed, Caylee may still be alive. I think if CA had allowed her daughter to go out whenever she wanted, not work and dump Caylee on the grandparents all the time, Caylee would still be alive. And GA and CA know that, which is why during one of the jail visits, CA announced that when "all of this" was over, casey would not have to work and could be more free. It was like a plea, a prayer: "Just make this nightmare end. Give me back Caylee. I'll give you whatever you want." Sadly, she knew deep down it was too late. I am not saying they are to blame, btw. I'm just saying that casey's final motivation and the reason why the murder happened at the time it did was the squeeze she began to feel and what she perceived to be was her lack of freedom, due to her child. But until then, Caylee was accounted for and not locked away in some trunk.
I think casey resented Caylee but did not hate her. I think her hatred was reserved for her parents, mostly her mom, who began finally to try to hold her daughter accountable. A little too little, a little too late. casey also hated that her mom treated (in her mind) Caylee better. I think she hated her mom for being a better parent to Caylee and for trying to usurp casey's role in that regard. And she hated CA because CA is a crazy, personality- disordered person who made casey's life miserable and likely would have even if casey had not been an irresponsible, criminally minded sociopath.
IMO, casey made the cold and calculated decision to murder a child who got in her way, a child she did not truly hate and probably was even fond of at times. See, sociopaths can do that. They can make clinical decisions about the fates of their "loved ones" without having a history of being violent abusers or criminally negligent parents. They can decide to get rid of people they don't hate who they even enjoy from time to time. That's because the sociopath comes first to the sociopath and anyone who gets in their way is at risk to some degree. Their love is reserved for themselves as are their bonds.
No, I don't think Caylee was ever abused in a conventional sense by casey, until the day her life was snuffed out by a monster. However, there was something going on deep down that I would call abusive. casey didn't really love her child the way we love our kids. She didn't really have that strong bond or familial connection. I think that when Caylee was born, casey saw her at times as an extension of herself, without an independent soul or personality. When she looked at Caylee, it was like looking into a mirror, in a sense. So, she was okay with her. As Caylee grew, she became more of a ball and chain and more like an unwanted sister who was taking casey's place as the family princess and forcing responsibility on casey that began to negate the novelty of having a cute baby to tote around and having people gush at what a great mom she was. And so, Caylee was murdered.
Yet, prior to that murder, despite an absence of any conventional battering or neglect on casey's part of Caylee, at no time was there what I would call a normal bond or level of affection. Hence, the eerie videotapes of Caylee, being taped for long stretches by an unresponsive parent who was simply looking into a mirror as she taped and not seeing the real, live, breathing human soul that was staring back with confusion at the lack of connection and stretching her little arms out, vocalizing as best as she could to get some response from the person she was left alone with, who was behind the camera. But the response did not come, the eerie silence continued and the little face crumpled in confused anguish. That to me is abuse and that's the only kind of abuse I really feel occurred here. And, it's really enough.