I think it's easier when there's a single polity that represents the "entirety" of that languages speaking community. Nobody controls English in the same way - I'd say the US and UK have equal claim to being able to formalize language changes, but good luck getting 2 billion people to follow them.
I think for those languages (I know French and German have them, unsure about Polish) there is a central body which "controls" the language, meanwhile in English we don't have one.
There is one for Polish but I think English speakers overestimate the power such bodies have over people :)
The only power they have is influencing the way kids are taught at school. Everything else changes by social pressure and exposure - most media choose to follow the new convention and people get used to it over time.
The changes are very gradual - the only big one I remember was in 90s - changing how "not" was written with adjectives and adverbs. The rules got much simpler so few people complained.
So the only power such bodies have is being able to influence the entirety of the next generation of the speakers of the language? That's surely some amount of power that nobody holds whatsoever on the English language. Israel was able to use the educational system to revive a millenia-dead old language, that's quite a lot of power.
I meant the direct influence would only be noticeable after decades, but because of media and social pressure after a few years most adult people switched.
