I was looking around for a step down converter for a home robotics project, when I bumped into this one (image below). In the description it says
Can not charge iPhone and Samsung cellphones; But can charge other phones.
Although I'm planning on using it to power a Raspberry Pi and not a phone, I was simply wondering: why on earth would those specific phones not be able to be charged by a regular 5V 3A power source? I mean; power is power right?