It is almost impossible to show how tame the fur farm foxes on Prince Edward Island really were, but in addition to the photos - of which there are more than one [1] - there are also written reports about how tame the foxes where [2]:
"Dr. Frank, among other things at Montreal, had a pair of tame foxes lead about on the main streets, driven around in automobiles and taken to a public dance, where the girls did the fox trot with these foxes around their necks, and all this was photographed, moving pictures taken, etc., and to cap the climax Dr. Frank hired two airplanes, took up a pair of foxes in one and from the other airplane a photograph ground out several reels to be shown in the movies in the near future."
How common these traits were is another difficult question. But given that there was prior selection for tameness and that Belyaev specifically looked for those tame foxes to include in his experiment [3], it does not seem so surprising that this trait very quickly became more common.
[1] https://www.washingtonpost.com/science/2019/12/03/tame-foxes...
[2] https://babel.hathitrust.org/cgi/pt?id=nyp.33433090788674&vi...
[3] https://doi.org/10.1002/bies.200800070