You're certainly right that few people would pay as much for the device if "all" it could to is serve as a gateway to human knowledge. I don't believe that the knowledge part is an active ingredient in the equation, but I don't disagree that it's a nice bonus.
> Imagine having to go to a library to get directions for a short daytrip or book an Uber a day in advance. The frustration that would cause and time it would waste is enormous.
I grew up in a time when that was quite normal (well ... day trips to somewhere unknown? that's rare!), and it wasn't so bad, and certainly didn't feel frustrating. It's hard to believe, but we managed to traverse the city (and even the country) without navigation assistants too ;)
> How many people in a poor neighborhood would shell out for a knowledge-only device or spend hours after a hard day shlepping down to a library?
Workers in Germany used to organize voluntarily in educational organizations some 150 years ago to advance their knowledge and social situation. Since it was forbidden to do so before the revolution of 1848 by the ruling elite, they got together under the guise of singing or sports to share knowledge (and socialism). They'd happily spend hours at the library had they been allowed to.
I'm not arguing against your point, but I do believe that it's class-dependent. If you're educated, you're likely to use your phone for information and entertainment. The lower the class, the larger the entertainment part grows. The idea of social liberation through knowledge is a noble one, but I wouldn't hold my breath. I don't believe that the availability alone will help for large parts of the population, and we shouldn't rely on that to advance their circumstances.