A native speaker told me that "In conversational informal speech you use Saxon genitive for everything, regardless of whether it is animate or has anything to do with human activity.The rock's color. The river's sound. The bird's song. The wall's color The car's engine The shoe's sole The game's object".
These are all acceptable in casual spoken AmE. Prescriptivists will likely wail and bemoan with much gnashing of teeth its use with inanimate objects, particularly in formal written English, but it's common in informal speech.
Regardless, it's a stylistic guide/norm than an actual grammatical rule. There are cases where the possession via the preposition 'of' does sound better than via apostrophe s. Such cases are subjective, and also depend on context and structure.
Something like "
Education's value is the ability for personal growth" is tolerable (to me) for conversation, but with something like "
He believes in education's value", I'd prefer him to believe in the
value of education instead. It just sounds better, even as casual conversation.
Other cases to avoid the genitive possessive is with location, because it's potentially confusing.
He's the manager of a restaurant in our town reads better than
He's a restaurant's manager in our town.
Certain titles work better with 'of'. You'll frequently hear "
Mexico's President" on US news networks but never "
The United States's President. That's always expressed as "
President of the United States" or "
US President" The first is awkward to say.
