Why do black olives typically come in cans and green olives typically come in jars?
It's for marketing purposes. People who can see the food inside the jar are more likely to buy it. Subconsciously a tall jar full of olives is more pleasing to the eyes than a can which is full to an unknown percentage. Another good thing about a glass container is that it is resealable, so the olives remain fresh longer.

So why don't they do this with black olives? Jars are more expensive than cans or other cheap plastic containers. Green olives seem to be more popular in american cuisine than black olives. Companies have more budget to afford more expensive packaging for green olives than for black olives. It also depends on where the olives come from - I eat a lot of olives from a niche Greek grocery store, and all of the olives (green or black) are in plastic containers, most likely because of the economics of the region from which they were imported.