Two of the most persistent controversies in the world of whiskey are the whiskey/whisky spelling issue and the "Jack Daniel's isn't bourbon, or is it?" issue.
I'm not going to rehash either of them here. If you're interested, the spelling issue is explained here and the Daniel's issue is here.
As I say in the later essay, the two are similar in that there is much less to both than many people think. They are both information usually obtained very early in a whiskey drinker's education, right after they learn that "smooth" is the catch-all attribute for any whiskey they like, but before they learn that using it marks them as a novice.
Why is "a little knowledge" dangerous? Because it makes a person feel superior, which makes them defensive when they subsequently learn that the reality is more nuanced than they realized.
Typical is the person who wants to call the manager to the table because a server has included Jack Daniel's when listing the establishment's bourbon selection. When you ask a server what bourbons they have, "Jack Daniel's" is the least of the possible wrong answers. I've had them list everything on the bar that isn't clear, including Crown Royal, Johnnie Walker, and Southern Comfort.
In that context, Jack Daniel's is actually a right answer.
Is it ironic that the best-selling bourbon-type whiskey isn't bourbon? Yes, but it's not particularly important. When you only have a little knowledge, you don't know this, so your outrage about the ignorance of the server or bar actually betrays your own ignorance. Neat how that works.
Here's all you need to know. The only reason Jack Daniel's isn't labeled as bourbon is because its owners don't want to label it as bourbon. All of the reasons people cite for why JD can't be labeled as bourbon are nonsense. The only ruling on the subject that the feds have ever made was made at the request of the company, seeking permission to call their product Tennessee whiskey instead of bourbon. They did this because they were afraid they would be forced to label it as bourbon and they didn't want to, so they lobbied for and received acknowledgement of Tennessee Whiskey as not-bourbon..
Similarly, the only reason people worry about using the spelling "whisky" when talking about scotch is because the Scotch Whisky Association makes such a big damn fuss about it.