It is not Jack the Ripper

I watched The Lodger on TCM tonight. In the introduction, Ben Mankiewicz said the film took place in the late 19th Century. In the goofs section for the film here on IMDB, it said that it showed the London Bridge six years before it was built.

The film shows motorized vehicles. The film shows an electric reader board (as used to be on newspaper offices in years past). The film refers to radio.

While the film may be about a Jack-the-Ripper-like murderer, it is not about Jack the Ripper. The story is clearly contemporary to the time that the film was made. Why do so many people think it takes place in the 1800s?