As long as it's "single page bound" JS like this, I honestly don't think it matters one bit.
Reusable components and utility libraries is something different, of course.
Reusable components and utility libraries is something different, of course.
I'm just guessing, but the site was probably not developed by a technical team, probably some web shop that specializes more on the design/layout/content side and not on the JS side.
So it's likely it's the work of a non-developer than a bad developer. The net result is the same (bad code) but the distinction is that the code was possibly written by someone who wouldn't even be considered a developer.
a) Because it isn't "right" as such. It's just "better" if the code is going to be reused. Which it isn't.
b) The code style serves as documentation. I can clearly read from this code that it's not a reusable component. It is now easier for me to get an idea of how and where this code is being used in the site.
c) Personally, I'm wary of "pre-emptive generalization". Every layer of abstraction makes the code slightly less readable. Also, unless there exists at least two use cases right now, you're not likely to get the reusability right anyway.