When I first started self-publishing, Amazon had two options.
You could go direct to digital, or use their paperback portal, called "Createspace."
The latter had a much more flexible way to develop a book cover, and since you could port paperbacks into the Kindle system anyway, that was the way I always went.
But that's gone away, so now cover options are pretty terrible. I'm thinking of just doing the whole file on my own. Well, after this book, that is. Right now I just want to finish.
I suppose the ugly truth is that e-books pretty much dominate publishing these days. What's not to like? Money without actual printing costs. I certainly sell more e-books than paperbacks, but I myself do not buy e-books. I'm a traditionalist, I guess.
Obviously, this is coming up because Long Live Death is inching towards publication. I may yet revise the cover, but I'm going to see what I can squeeze out of the Amazon interface first. Three Weeks with the Coasties used a default cover, but it worked with the subject matter. The same was true of The Vampires of Michigan, but I want something a little less abstract. We'll see how it goes.