Do you think money grows on trees?

With some watering and a bit of sunshine, the roots of many trees sink deep into the earth and they eventually become self-sustaining, meaning they require no further help from a human to continue living. After a tree has grown and matured, they'll start producing a variety of fruits depending on what kind of tree it is, and trees do this for free! To benefit for this, all you have to do is walk into your front or backyard and gather as much fruit as you need. The point? It takes little effort on your part to enjoy the plentiful bearings of a tree.

On the other hand, money is the opposite, it's not nearly as easy to come by. You can't just walk up to a tree and gather cash from it like you would fruit, no, it requires considerable effort to earn, and some people, especially kids, may not always understand that. Thus, a comparison is drawn from these two things and you get this expression.

This phrase looks to be a relatively recent one from what I could tell, only emerging in writings near the end of the 1800s. For example, the Statesville Landmark newspaper from 1891, reads:

"Money doesn't grow on trees here yet."

Also, I found this to be sort of silly, but there's a line in the book titled Oakland "Athens of the Pacific" from 1897, which reads:

"Gold doesn't grow on trees in Alameda County. Don't come here with an idea that it does."