You can't beat free. Also they benefit because they can taylor the code to their specifications. Any program can participate in this information exchange, so long as the program uses the protocols. It's almost like having a translator to help a Spanish speaker and an English speaker have a conversation. Open protocols simply means that anyone has access to them.
Open standards is along the same lines.
Again 'open' means that anyone can have access to the standard. If I want to travel around Europe with a hair-dryer in my suit case, I need to make sure the electrical standards are equivalent in the various countries I'll be visiting. If a company succeeds in de-commoditizing a protocol, they've basically made it so that no one wants to develop an open source equivalent. It's also called protocol pollution. Like hackers aren't bothered by Adobe Photoshop because GIMP is around and uses most of the same protocols.