I hear about it all the time: planned obsolescence. People can't believe that their computer parts are already breaking and their iPhone started to slow down just days before the next generation of the phone was released. Your TV seems to be programmed to have bugs whenever the manufacturing company wants to push a new product. Companies break their own products to get you to buy more of the same product: light bulbs, phones, batteries, cars, microwaves, computer screens, and even your car key transponder will all stop operating eventually. Either the marketing team or the designers wanted it that way, right?
Wrong. There are many factors that lead to degradation in performance or outright failure of a product. The root cause is usually cost, although there are many other potential causes.
Farewell, trusty Toshiba Satellites of yore.
Your laptop original equipment manufacturer (OEM), such as Dell, Toshiba, or HP, sells batteries that are much more expensive than the batteries from third party suppliers. Why not just as easily get your next battery elsewhere for a fraction of the cost? This is much cheaper in comparison with purchasing a several hundred dollar battery from the OEM, despite each battery appearing to be identical.
A host of cheap batteries on eBay waiting to kill your laptop slowly.
There is a difference, however. Buying a battery from the same company that made the laptop means that the same engineer who designed the power supply in your laptop also helped design its battery and the interface between them. A person or a closely coordinating team analyzed both circuits and both mechanical assemblies and decided on the best possible design for their product. A similar process also takes place for the company making the cheaper batteries. However, they have a different set of goals in mind for their product: while the more expensive OEM wants to sell a high-end package of parts that is associated with a reputable brand name and will carry on a consistent level of quality, the replacement battery manufacturer doesn't care about quality. They produce cheap batteries that people want to buy to replace a defunct battery in an old laptop. They aren't worried about the customer retention or satisfaction, and so have the flexibility to decrease investments into the product in order to cut costs.
This applies to all products, not just electronics. Latches on pencil cases aren't meant to fail after some number of years or some thousands of operational cycles; they just fail. It is the same with laptop keys or paper clips or duct tape. While there is little functional difference in a product being "designed to fail" at 50,000 operations and the product failing spontaneously due to engineering and material characteristics at 50,000 operations, there is a huge difference in our understanding of how and why that failure happened while you were using it. No company or engineer wants a product to fail at a desired point in time. They can take advantage of a market that desires products that aren't particularly reliable at the benefit of a reduced cost to the consumer. But, if the product could feasibly be made to last forever, then they would make them to last that long—or a different company would do so and reap the financial benefits.
Products fail of their own accord. The product is always being designed around a set of parameters (material properties, mechanisms, cost, time, industry regulations, previous products) and an investment into one of those constraints (for example, stronger and stiffer plastic) means trading off an investment into another (each device is more expensive). At the end of the day, those constraints are set in stone and there is very little room to expand how your design utilizes those resources.
The third party suppliers of the incredibly cheap laptop battery made a deliberate tradeoff. And while their cost cutting might be extreme, every manufacturer makes similar choices. Even the OEM battery is not designed to be the perfect product in terms of lifetime. Proper understanding of those constraints is crucial to realizing that companies don't design products to fail. They fail in exactly the manner one would expect them to because changing that would have conflicted with how the product is sold. While you can always blame Motorola for making a charging plug that bends too easily or GE for an incandescent that goes out every 6 months or Apple for making a phone with software that is outdated in exactly two years, you have to understand that they made those decisions due to consideration of the product as a whole. If they wanted more lifetime from the product, they would have had to cut costs elsewhere (so maybe it wouldn't be as aesthetically pleasing) or increase the cost of the device.
An array of obsolete batteries.
Consumers will be unhappy if they pay $150 for a battery that stops holding a charge after about a year, but would anyone buy an otherwise identical $210 battery that is said to last an average of 2 years? Maybe. But there is no way for the average consumer to know how long each individual battery is going to last and, frankly, the majority don't care. Unless the more expensive battery comes with obvious additional features, customers won't bother dishing out extra money for most commercial products that are only expected to last longer. The cheaper battery isn't designed to fail first. Rather, it simply is made from a selection of slightly cheaper components or processes because the company thought that would sell better. A $25 battery that is ostensibly identical to the other two more expensive batteries almost certainly has some difference in expected quality. None of the three batteries is designed to fail; they are products designed a certain way and sold at a particular price as determined by the company. The resulting lifetime is a reflection on that quality.
The concept of an electronic product being designed to fall apart is a fallacy. Product failure is the result of a decision that involves many more factors than just the expected lifetime of the product. The concept of planned obsolescence is more accurately described as a complex interplay between how the designer wanted to make the product and the price point at which the consumer will buy the product. In short, electronic products aren't designed to fall apart: they are designed to last as long as possible and still be a product that will sell.