19th century moving roads

The moving electric sidewalk (street of the future) was presented at exhibitions in 1893 and 1900 in Chicago and Paris. It was 3.5 km long and had 9 stops. Fourteen thousand people could pass on the sidewalk at the same time. The exhibition of 1900 lasted 7 months, and during that time 50 million people were able to ride on the electric road. It was said that such sidewalks would soon be in operation everywhere, but we never got to see them.

I wonder why?