AIPAC has shaped much US policy over the last sixty years and in consequence Israel has benefited immeasurably. Build settlements illegally on Palestinian territory? No problem! Ukraine, conversely, can't control US politicians through campaign contributions, media activities, etc. and thus from the perspective of US politicians is inconsequential. The fact is, the US government has always been bought by special interests and we can't expect US politicians to act in the national interests of the USA when their decision calculus is far more personal (e.g., "who can give me the most money for my re-election campaign?").