While I can't and wouldn't speak for Brad Klein, I am in the midst of reading his "Rough Meditations". The essays on Caddying, are to say the least, telling. The term, walk in the park, is often used esoterically by the cadets to describe an overall day, much like "day at the beach" is used.
So perhaps, it being in quotes, is meant to convey some intrinsic value that is hard to put into words, and is not necc meant to be literal. I think the verstilaty it evokes is a personal one and therefore means different things to different people. Trees notwithstanding.
I find it hard to believe that the general public, who have a propensity to ride in carts, would "get it" if it were literal.