''-ise''
They are treated equally. We just don't want to duplicate the information, that causes maintenance problems. How many countries favour it is not relevant for this case.
But why is -ize in preferred in favour ahead of -ise? Wouldn't be a technical solution the best, which synchronises both articles automatically?
Maybe this could be done at first only with things like ise/ize, yse/yze and labelled/labeled and all those which have no different meaning. So that the content of the article "minimize" is getting embedded into the article "minimise". As far as I know, there are similar solutions for Wikipedia, where the embedded template depends on the used spelling.
If you want to change it, you should start a new topic at Wiktionary:Beer parlour.