Audiences (mostly) don’t come to see the venue, they come to see the act.
It is true that Google books does not supply books to readers on a commercial basis. It is true that Google books supplies audiences to advertisers on a commercial basis.
For Google Books, the principle tool used to draw an audience is ;books.
For Google Books, books are a tool of trade , they are used to create a product ; ‘audiences’ that is suppled to advertisers on a commercial basis.
Google’s use of these books as a tool to create an commercial product : ‘the supply of an audience’, is a commercial use by Google of these books .
A worker on a building site asked the foreman, if he could have a wheelbarrow of sand to take home as he was building a sandpit for his kids, the foreman said ‘fair enough’. The worker continued to take a wheelbarrow of sand home every Friday evening for the next few months, before someone noticed that he wasn’t bringing the wheelbarrows back. Everyone is focussing on the sand, and not on the missing tools of trade. The worker was taking some sand on a’ fair enough’ basis, and he was also at the very same time stealing a tool that could be used for a commercial purpose.