To my understanding (which can be wrong) these gas turbines are not backup generators, but used as primary or supplementary power sources during normal operation where the grid cannot supply (or when grid cost is unfavorable). In one clip (which is a bit sensationalist so I'll refrain from posting it as it may derail) shows a park of some ~24 large gas turbines - each of which sized like a small building - with about half in operation at that time.

Indeed, there is some noise from backup generators when tested (or in use), but with a bit of preparation, good palcement and sequential testing you can make that not too disturbing.