I ate all the bananas and oranges on my moms fruit platter
Why did you eat all of that fruit?
She has so many bananas and oranges, she can easily replenish it
It's not okay to eat more than your share of food. Eating all the specific fruits and leaving none for everyone else may upset them. People may think you're selfish if you don't share.
I don't get why she buys so many bananas and oranges anyway.
Whatever the reasoning behind her buying so many, it doesn't change the fact that you should still respect the rest of your family by only eating your fair share.  How would you feel if one of your family members ate all of your share instead?