It is a sad situation when parents give into their children for fear that the kids will stop loving them. The most common word in a parents vocabulary should be 'no.' Unfortunately, too often, it's 'whatever makes you happy, punkin'.
I too was very confident in my ability to control the way my kids behaved, before my kids became teenagers. I was sure that faith, wisdom, patience, strength, and the influence of the Church would make my adorable children behave so much better than the kids in their school and neighborhood. I'm now more compassionate toward the parents of difficult kids because even the best parents and the best kids can take a wrong step.
BTW, parents don't necessarily have to pay for boob jobs. As long as Visa and Mastercard offer credit cards to 18-year-old girls, they can do what they like. I know girls of that age who have paid for cars, horses, travel, Lasik, and yes, boob jobs, with credit cards, without even troubling to inform their parents. The parents of the dead girl may not even have known the daughter was doing this. Whether they knew or not, they may not even have been in a legal position to say no to a self-supporting adult daughter. We really do not know.
(On the other hand, they may have known very well and may even have approved. And in that case your disgust with them is well deserved.)