Have you even used them on your model trainz layout? I have. They operate just like engines in Driver and can run on track invisible in Driver.
Using my big imagination, this could be a big technical challenge on a physical scale model layout. How could the fake mechanical horses be made to trot like real-world animals? It would take some clever scale-model robotics indeed but they did it with full-size fake horses in the Westworld film and the human guests could even ride the mechanical ponies.
Yes, the moving horse-drawn wagons will give your layout a bit of a science-fiction futuristic feel. If there are any horse-drawn wagons on model train layouts these days, they are most likely static scenery.
You will get some typical railroad sounds with these wagons and buggies, however. The hissing of air brakes as if the horses are farting, perhaps?
Other non-train vehicular rail equipment for both train simulators and perhaps physical layouts are what Lionel Trains used to catalog as "powered units", which are not the rolling stock used to assemble RR trains.
What's next, cog railways for Trains and the scale-model hobby? Working San Francisco cable cars for our hobby?
These include RR inspection cars, trolleys, operating motorized handcars, MOW trucks, motorcars and speeders.
In model trainz, I have made the Amtrak MOW crane truck (an engine, actually a locomotive in disguise by superlaku) run over bare ground, as in a railroad yard, with invisible track and get onto and off of visible rails of the main line using an invisible junction and an invisible lever. This would take some clever ingenuity to make an operating physical scale-model MOW road-rail vehicle able to rail and derail the tracks.
