1. Legal second-guessing: Here, Apple used a particular design for its ear buds. The second-guessing comes in where courts say, "yes, we know that you made these design decisions but, were you to use some alternative design, or to include an additional warning, you could meet all the legitimate goals of your product while at the same time reducing the number of potential injuries to your customers at no appreciable added cost." The law then defines this deficit (or lack of warning) as a product "defect," not because the product can't be used in a safe way but because the second-guessers have proclaimed that there is a safer way that might be used that still achieves the product's goals at no significant additional cost. Experts are then trotted out to say, "I am an authority on ear buds and the design used by Apple creates avoidable risks and hence needless injuries to customers." The matter is then tossed to a jury for a crap-shoot outcome. Welcome to the modern world of product liability law.
2. Class actions: The above approach to product-liability law is made far more pernicious when the class-action vehicle givers the second-guessers the opportunity to multiply their damages for every product sold, whether or not it ever caused any injury to anyone specific. When combined with potentially surprise sources of liability (e.g., ear buds that harm no one physically in 99.999% of cases suddenly becoming "defective" because a theoretical argument might be made about how they might be safer), the class-action vehicle turns law from a sleepy-time industry where individual practitioners wait around for individual clients with real injuries to retain them to sue for compensation into a mega-industry where creative lawyers can find nearly infinite ways of creating potentially massive liability risks for manufacturers. Welcome to the world of jackpot justice.
3. Pleading rules: Modern pleading rules make this stew even more lethal. In essence, the modern world is governed by what is called "notice pleading." The idea is that all one normally has to do is state in broad terms what happened to give rise to a legal claim and the case is set on a path to get to a jury. In recent years, some of this excess has been cut back as these rules have been modified to a degree. Nonetheless, modern judges tend to have very few tools with which to hack away at frivolous claims and to dismiss them before they can reach a jury. The result is that defendants facing even the most bizarre-sounding of legal claims are forced to run up major legal bills dealing with such claims through an expensive process of pretrial discovery and trial. It is not unusual for a modest case involving middle-class parties to go for one to two or more years in such cases and to cost each side six figures in legal fees. In the case involving Apple and the ear buds, the legal costs would easily have run $10M and up if the case were allowed to go forward for a year or so.
4. Absence of personal responsibility: The modern trend in law sees courts as being protective of citizens in ways that used to be regarded as unnecessary - hence, courts today routinely come up with new or expanded theories of liability that they see as taking on the big companies for the benefit of the larger society. One can debate this either way on the merits but it is a fact of life and it does lead to ever-wider bases upon which defendants can be held liable.
Put all the above together and it is no wonder that common sense goes out the window. It is no longer an issue of "did this party use this product and injure himself in the process and, if he did, did the manufacturer do something negligent or did the product itself not get manufactured properly or safely such as to cause an injury." Instead, it is: "has this party alleged broad claims that show that all purchasers of this product might be subjected to risks that could be avoided with simple warnings or with simple alternative designs and, if so, how will a jury decide that question after hearing all the experts hypothesize about the various alternatives and after hearing experts speculate about how this manufacturer is causing hundreds of millions of dollars of injuries to a broad class of people who might be using this product."
Thus, the law moves from individual cases involving provable cause and effect to group cases involving battles of experts and juries being given enormous power to impose liabilities on product manufacturers.
In this context, it is quite unusual that this case got tossed at the first stage and even more so for the appeals court to uphold the trial judge in that action. Of course, with open forum shopping being the norm in today's world of litigation, other cases can easily be brought in more receptive venues with outcomes that are far from predictable. This unfortunately is how modern litigation works.