donbrew

That was the point; each manufacturer has its own proprietary design. If you have a Ryobi you need a Ryobi saw. Even Black and Decker brands are not fully interchangeable.
There are adapters available to make battery A fit tool B.

Oldblue

It’s a huge money maker, and if your battery tools wear out, then there’s a good chance the batteries won’t be compatible with your new replacement device.