I think that the use of em-dashes specifically is a result of either the preprocessing of the training data or postprocessing of the generated text. I doubt that the material the models are trained on (i.e. Reddit) contains more em-dashes that hyphens in the position of sentence breaks.

But it definitely gets the use of dash as sentence break from people writing like that. If you ask ChatGPT in another language, whose users don’t generally use dashes, e.g. Slovak, it won’t use then as much.

There are dozens of us that know how to type en- and em-dashes! Dozens I say!

In my country we have these:

This is a dvoukolák (lit. twowheeler). According to the internet it can carry up-to 240 kg. Dvoukoláks often have bigger wheels and they’re not collapsible.

I looked on American Amazon and on Walmart’s website and I couldn’t find anything like it. Bike trailers seem to be closest to a dvoukolák.