I'd guess because for a lot of us in the USA, public transportation is insufficient to meet our needs. I'd love to take a train from home to work, but there's no train line that's anywhere near my house. They're building one that'll go near my work, but it's not done yet. Busses are available, I suppose...but the time it'd take to get from home to work or back would be a lot longer than driving takes, even in heavy traffic, given that I'd have to transfer several times.
For longer trips, again, the infrastructure just isn't there. To visit my sister, for instance, requires taking a bus if I want to take the public transportation option. My (step)son takes the bus to go see his dad (who lives in the same city as my sister) since he doesn't like driving, and it takes a good 2 extra hours compared to driving. We should have train service, but no...Scott Fucking Walker killed the project back in 2010 when he got elected governor of Wisconsin.
I have vague, terrified memories of watching the Rankin/Bass *Hobbit *movie in first grade back in...uh...1986, but it obviously didn't make me into the fan I've become. I hardly remember anything about it other than Bilbo climbing the tallest tree in Mirkwood and the spiders.
My next introduction to Tolkien went much better when our 7th grade class got assigned to read The Hobbit for language arts. From the first look at the map in the front of the book I was fascinated. I'd just started getting into (A)D&D and fantasy in general, and finding the wellspring from which much of that material came from was amazing. To this day, I think that The Hobbit is my favorite Tolkien book. I've read most everything Middle-Earth related outside of the HoME series, but the tone and the nostalgia of The Hobbit makes it special.