Also because generally in those cases you don't really want a guided tour of the whole product, you have a problem you want solving and you would like to see how to solve that problem with the product. Which either talking to a person who knows the product or reading through some documentation/guides does, but a guided tour generally does not (or at least does not do efficiently).

Or at the very least, at the price we're talking here, companies should be hiring a trainer who knows the product well, who can actually teach people and answer questions. not go through this, go through that, clicking that: half the things are not useful to their particular problems and shouldn't be taught at all to this group.