Fair Is Fair
If a grandparent decides to gift one of their grandkids $500, it’s not the parent’s place to scream “fairness” about their other kid not receiving $500. Look, what someone wants to do with their money is not anyone else’s business, especially when family is involved. If this granddad wanted to be fair by the parent’s standard, he could’ve given both of them diddly-squat.
Also, the grandson was giving something in return to his grandfather. He was going to ride around with his grandfather’s company’s logo on his car. Meanwhile, the granddaughter wouldn’t have done anything. It was a business transaction, not favoritism.