I don’t do any wild or spontaneous fermentation- I always use a a known yeast strain.
Some corn may have yeast on it some not- but you won’t know what kind of yeast you are getting– you can easily pickup a bad yeast or mold. In my opinion malted corn is not a replacement for yeast.
There are proponents of using wild yeast- I am not. I don’t want to gamble all of my hard work to luck when I can easily buy a good known yeast. With a known yeast I know how the yeast will perform — and I will have a consistency across all of my mashes which can easily be repeated.