From
https://en.wikipedia.org/wiki/Staphylococcus:
»
Staphylococcus includes at least 40 species. Of these, nine have two
subspecies, one has three subspecies, and one has four subspecies.
[4] Most are harmless and
reside normally on the skin and mucous membranes of humans and other organisms.
Staphylococcus has been found to be a
nectar-inhabiting microbe.
[5] Found worldwide, they are a small component of soil microbial flora.
[6]«
So those critters can be found naturally in soil almost all over the world. If you don't keep your Duckies in an "all-pillowed tiny room" (love that picture!) they will cut their feet and if they walk on natural ground those wounds can become infected. And it all depends on the current status of the birds immune system, similar to weather we humons get a cold or not when exposed to the Rhino-Virus.
I have seen wild mallards with bumble foot here in WV around natural lakes, ponds and creeks and they seem to do fine. My three White Layers who caught bumblefoot almost healed themselves after i initially treated the infection with some neosporin, grabbed Bazilla recently and to my surprise her feet are fine, small bumps and some bruises but no signs of infection. My Duckies get ½ shredded kale every evening which contains a lot of Vitamin C and in the depth of Winter i add a teaspoon of Vitamin C powder to their drinking water to boost their immune system and so far i had only three cases of BF.
It may also has something to do with the breed of ducks: The White Layers who had it were my heaviest birds, the fourth one is significantly smaller.
My Runners all have cuts and scars on their feet, but no signs of infections.
I will have a watchful eye on those Runner/Orpington mix drakes from August as they now are the heaviest birds here, two of them can reach 80cm (32") high, they can steal the sandwich from the patio table…
@Loopeend - There is such a thing as »Pink Eye« in the Netherlands, at least according to Wikipedia:
https://nl.wikipedia.org/wiki/Bindvliesontsteking - The »
Pink Eye« is slang here for
Conjunctivitis. If you think you speak and understand English, come and visit the U.S. - and become confused!

Took me a while to figure out what a »pain in da shoulder« is:
https://en.wikipedia.org/wiki/Post_pounder