The Manufacturers have little to no regulation of the claims they make for their product's effectiveness, nor control of the product once it leaves their facilities.
Live bacteria products may not have the the actual nitrifying bacteria, or even if it did, shippers may not have stored/shipped it properly.
Show me the science and let me prepare a couple of slides, from product off the shelves.
I wanna see live beneficial bacteria under my microscope.
The only product that ever showed the science and had live bacteria was the original refrigerated Bio-Spira.
I haven't checked the new Bio-Spira, nor any other similar product in over 5-6 years.
Having mature tanks/filters, I've never had the need to seed a new tank with such products.
I've always been somewhat dubious... Caveat Emptor!