Snopes[0] rates this as sort-of, but probably not the main reason

[0] https://www.snopes.com/fact-check/railroad-gauge-chariots/

In the finer print it rates it as, “Partly true, but for trivial and unremarkable reasons.”

This is the kind of quality material I expect to find on my dad’s Facebook feed.

This story is literally older than the internet, and widely know to not really be true. I'm sure almost anyone on this website has read of version of this hosted on some basic HTML site at least a decade ago.

This thread is mostly false.

Fact checked by Snopes (read the comment of motdiem: https://news.ycombinator.com/item?id=21099365)

The true source is from a humor site: https://aviationhumor.net/the-us-standard-railroad-gauge-is-...

England actually had at least one more competing gauge: Brunel gauge. Brunel thought it was silly to keep using the same arbitrary gauge and that a broader gauge would be more comfortable. Eventually it was decided to use the Stephenson gauge instead, though, and this became "standard" gauge.

It's an interesting example of a compromise where having just one standard is preferable to trying to find the perfect standard.