Doesn't sound very authentic.
No, the pasties aren't authentic at all—they actually have some seasoning in them! I don't think the owners are trying to duplicate what you'd find in the Upper Peninsula (or Cornwall). The flaky crust is different as are the chunky fillings. I also sampled a chicken curry pasty.
But seriously, a vendor selling pasties, empanadas, patties, etc. could do a ton without having to cook to order....
Yeah, for the time being at least, it makes a lot of sense to tailor your truck's menu to things that hold well instead of doing sandwiches etc that would be much better freshly made. Isn't there now some truck prowling the streets selling upscale tamales? I wonder if the Bridgeport Pasty folks have thought about a Jamaican patty-style pasty. That could be really good, though inauthentic.