Tin foil hat mode: The battery industry makes money from selling in disposable battery volume; if their disposable batteries last twice as long, their sales volume will drop by half.
Of course, if they manage to sell their 2x lifetime batteries for twice the price it would sorta even out again. But the customer, when faced with regular batteries and 2x priced batteries, will still pick the cheaper one despite the lifetime claims.
Yes but he's asking why the DEVICES don't incorporate the technology. If for example Apple could claim 8x battery life in their keyboard by adding a 10cent piece of kit you'd think they'd do it.
To fit the booster into the same space as a battery is cutting-edge, but to put a cubic-centimeter boost circuit next to your battery chamber is nothing special. If the boost circuit is too bulky, the battery is definitely too bulky.
A boost converter is a very common circuit. If electronics manufacturers could extend the battery life of their products they would. Many products are regulated to require certain number of years that their batteries must last. Smoke alarms sold in California must have a 10 year battery. If they could use smaller batteries to supply ten years of power, a product with that large of a volume could save millions of dollars a year. Financial motivation is a two way street.
Of course, if they manage to sell their 2x lifetime batteries for twice the price it would sorta even out again. But the customer, when faced with regular batteries and 2x priced batteries, will still pick the cheaper one despite the lifetime claims.