Because I work at a newspaper and have for years and I am knowledgeable of such things. Technically, I know that complaint is not #1 since the papers are there practically every morning. The example does not happen often, but sometimes presses break down and there is no paper and the hotels hear about it loudly and clearly from their guests, thus the #1 complaint.
As stated, hotels spend millions of dollars a year on newspapers and they would not do so unless their guests wanted it.