That's actually crazy to me. Like, a sealed, generic brand bag from the cold section of a chain grocery store vs a block purchased from the deli and shredded by hand? The difference is massive! Taste will vary between the two anyways but the texture difference is categorical. The pre shredded has grainy flour like stuff all over it, the manually shredded is completely smooth with no graininess at all. I can 1000% tell the difference in any kind of test you want to do.
Where are you buying cheese that this comparison isn't noticable?