Are salamis/pepperonis in the USA truly fermented? I've been exploring making my own salami and have learned that it is a lot of work! Not only must you make sausage, but you must also ferment it and dry it for many days. The fermentation piece seems especially tricky due to the work involved with fermentation starters and the risk of illness (or even death) if done improperly. The fermentation and drying periods also require fairly precise humidity and temperature.

This is why I'm surprised to see so much salami and peperoni in grocery stores. You can find these everywhere for very cheap, which I find surprising given the amount of work involved. I suppose it isn't that expensive if done at an industrial scale with meat scraps, but still, I have doubts that all salamis in the USA are indeed fermented.

Salamis are by their definition a fermented product. Are all or most salamis sold in the USA indeed fermented?
The short answer is yes, salumi produced in the US is a fermented product.  The process is different from salumi produced in Europe, but it is still a fermented product.  In the US, producers rely on rapidly lowering the pH by using fast acting starter cultures and higher curing temperatures (as high as 104 F).  Whereas in Europe, a lower temperature, and drying serve to render salumi safe. The curing times are longer, and often salt and nitrites are the main additions to create a safe product.  On an industrial scale, the complexities that you have discovered are all accounted for.  It is not a difficult process.

At home, it is a bit of work, but can easily be accomplished.  Work cleanly, follow accepted practices, keep an eye out for bad mold...otherwise, if you can create the right curing and drying conditions, you should be able to make your own without issue, though it will take a couple of attempts to get a feel for things.  A good starting point for those new to home cured meat products is whole muscle curing.  Try bacon, pancetta or bresola for starters.