No, this has nothing to do with vehicles, whether pulled by a tractor, or permanently parked somewhere on the wrong side of the tracks. This is about the trailers one sees, willingly or under silent protest.
(The name "trailer" implies that it will follow, not precede, but who would stay to watch this advertising if trailers actually followed the "main feature"?)
In the market town near where I was born, there was originally only one "cinema", the Hippodrome. Despite its name, no horse ever entered the place--let alone a hippopotamus. In the mid-thirties, another movie house was opened, the Majestic (a mundane structure that belied it's name). Each movie program was shown for a week, usually the main feature, a second feature, a "B picture", plus newsreel and a cartoon. Before the main feature, we were shown a "trailer", listing the next week's main feature, the principal actors and actresses (we never called female performers "actors" in those days), and a few clips from the movie itself. I never found these objectionable, despite the somewhat extravagant claims for the "coming attraction".
I seldom go out to movies these days, but when I do I try to arrive shortly before the stated performance time. No longer is there just one trailer, but five or more of films "coming shortly". In some movie theaters, they show trailers of films being shown at other venues under the same management.
However, there is one type of trailer which actually does follow the main feature--that's on TV. I can understand that on commercial television, it make sense to try to encourage the audience to tune in to the next episode, be it a sitcom or a crime series. We seldom watch commercial programs (other than the venerable 60 Minutes), so this doesn't annoy us.
We do watch programs on PBS, in addition to our regular dose of the PBS News Hour. I have two criticisms, one of which has nothing particularly to do with trailers: the tendency to broadcast loud "incidental music" over dialogue. But what really distresses me is when we've watched an episode of some excellent series, such as the just-completed Downton Abbey, we are subjected to "scenes from next week's episode". Yes, one can always switch off the set; also, thanks to our DVR, we can rush through that unwanted material without losing anything that we want to watch.
I suppose even in public broadcasting, there is an incentive to try to hold on to as many viewers as possible. In my case, this just turns me off--especially if a character is shown in a death scene--or making a miraculous recovery.