I believe this is a quote from the White Pages -not sure, but what I'm sure of is that it embodies the true meaning of Steemit's values:

"Everyone’s meaningful contribution to the community should be recognized for the value it adds."

When you say "I just saw a post on Steemit that was merely one person who took photos of his backyard and it is making hundreds of dollars!"

Well, here's my humble opinion:
Maybe it's the first time that person HAD a backyard. Or maybe he worked his tail off working on it and wanted to show it off. It's evident that whoever upvoted it found it to be meaningful enough or valuable enough to bestow a big reward to it --for the same reasons, maybe? Who knows... What is valuable or meaningful to you, may not be to others--and that's cool!

That's exactly why I love Steemit. It gives us the freedom to post and curate ALL sorts of things! Whoever created this wonderful spy-free, censorship-free, and ad-free platform for FREE, is a freaking genius, and I'm grateful to him/her/them.

The two meanings of the word FREE are covered here:

Free as in freedom to post what WE consider valuable, and
Free as in the Steem rewards we receive for posting AND curating.

With love,
@blogstar