Black olives are available in jars in the US as well. They are just a specialty item similar to higher end jarred green olives.

Black olives in a can and green olives in a jar are also available in commodity style qualities. So this is better labeled as "why are commodity black olives in a can while commodity green olives are in a jar".

Yeah, in Germany you can find both kinds in glasses, cans, or plastic pouches. However, I think most black olives here are simply green ones, colored with iron. I found it hard to find real black olives in my supermarket unfortunately.

Also, I think the botulism issue is prevented by having an acidic environment.

Similar situation in Finland (except olives in plastic pouches I have yet to see).

Canned olives in the US are a specific type which are artificially ripened. Is that the case with the olives linked in your post? (I can't read Italian.)

Same in France. Maybe it's specific to country that have to import olives from far away ?

Yeah, in Canada Kalamata olives can be found in glasses (but black olives are in cans)

You can also order them in some sort of plastic container from Walmart: https://www.walmart.com/ip/Discontinued/37620615 (the URL says "discontinued" but it appears that you can still order them)

>Maybe it is a local (US) thing, here in Italy/Europe you can find black olives in glass jars just fine

In India too.