The Ezee was not made by Scott and Fetzer, but rather by the Frantz Premier company, who was making the Frantz Premier (designed by James Kirby) electric vacuum since 1910. There is absolutely no reason it's on the Kirby Company timeline as it was never their product. In one of my old VCCC newsletters is the ad for it as well as the electric Frantz Premier.
I imagine that they sold as many as they could make, for the short time timey made them. Frantz Premier was bought by General Electric in 1918, who would have never made anything "non-electric".