We think ads in books is a New Thing.
Broken Toys, a novel by Anna Caroline Steele, was published in 1884.
Right past that cover, we get this:
Ah, are we at the book now?
Now we are:
And after The End, we get:
And then more ads:
Some day we could wind up with all eBooks being free and stuffed with ads like that.
At one time everyone thought Internet advertising would be restricted to a single banner ad.
And look where we are now.