Having first read your comment, the photo wasn't as bad as I expected. The supports don't look too unreasonable for a single wooden car with two passengers. Modern trains are an order of magnitude heavier--~20 people and a gross weight of ~20 tonnes.

A video of the coaster in the photo exists (the playback framerate seems somewhat too fast): https://commons.wikimedia.org/wiki/File:Flip_Flap_Railway_ea...

Modern tubular steel rails also allow for rickety-looking yet safe single-car coasters: https://commons.wikimedia.org/wiki/File:Rat%C3%B3n_Vacil%C3%...