>The large, mild form is called bell pepper, or by color or both in North America and the United Kingdom, but typically called capsicum in New Zealand,[8] Australia, South Africa, Singapore, and India.
It does seem strange that even anglosphere countries in the eastern hemisphere ended up with a different name for some reason. Presumably it was also called that in the UK at some point too.
Some other differences in Australian and UK usage are zucchini vs courgette and eggplant vs aubergine. Not much of a French influence down-under. And Italian immigrants dominated Melbourne's fruit and veg trade in the 1960s.
Perhaps it became common in all of these countries at the same time, long after colonisation, leading to different marketing/naming between these countries.
I had to look it up to make sure you meant (US: bell) peppers.