Okay, this character misconception always drives me insane - no offence. I hate it when Petunia is always known as the one that is suppressed by her husband, or so like her husband that she wouldn't care for Harry. This is not the case.I have to agree that Petunia taking care of Harry just doesn't fit. Dudley tries to, in his own way, but Petunia is so very Mrs. Vernon Dursley that I think she wouldn't dare.
The reason Harry is treated the way his is at the Dursley's is because Lily and Petunia pretty much hated each other. Vernon came into the picture long after Lily and Petunia's relationship was broken. It is because of Petunia that Harry is known as a 'freak'. Who knows what Vernon would think of witches and wizards had his point of view not been warped by Petunia.
Here's a two quotes to back me up:
Philosopher's/Sorcerer's Stone - Chapter Four.
This is Petunia calling her sister a freak, not Vernon. The hate that Petunia has for Lily is clear."I was the only one who saw her for what she was - a freak! But for my mother and father, oh no, it was Lily this and Lily that, they were proud of having a witch in the family!"
Here's a quote a few sentences later:
Again, Petunia says this. Vernon doesn't know anything about Petunia's 'freak' sister apart from what Petunia would have told him in the first place - and we all know what Petunia thought of Lily. In DH we learn that it has a lot to do with Petunia's jealousy of Lily, not Vernon's jealousy."Then she met that Potter at school and left and got married and had you (Harry) ,and of course I knew you'd be just the same, just as strange, just as - as - abnormal - and then she went and got herself blown up and we got landed with you!"
So, please, don't say that Petunia is the 'good' Dursley. All of the prejudice towards Harry came from her in the first place!