I gotta be honest: I haven't figured that out either.
I always guessed it was because more American Jews than Israeli Jews are secular/non-practicing Jews and they tend to be socially liberal. :dunno: More than a few of the secular American Jews that I know are opposed to Zionism, though they're not opposed to Judaism or Israel's right to exist. If I'm not mistaken, Bernie Sanders and Gloria Steinem are in that group. I've noticed quite a few Jewish feminists speaking out against Israel on human rights issues. Even the ones who are prominent in the business world talk the liberal talk, even if they don't always do what they want others to do (like ol' Harv "The Perv" Weinstein).
A lot of the demographic groups that liberal American Jews support aren't seen positively by Israel's chief (for those of Sephardic origins) rabbi, Yitzhak Yosef. He's not exactly a real big fan of Blacks, homosexuals, women (who don't know their place), Christians specifically (called Jesus "the evil one"), gentiles in general, et al. The other chief rabbi (Ashkenazic people), David Lau, I don't know much about. I have no idea how socially liberal or conservative he is. My guess is, he's to the right of center, but I don't know.
To me, this is an interesting question. But it's such a touchy topic that it's almost impossible to have a rational, unemotional, intelligent discussion about it on the internet... and certainly not in public. I'd also like to know how & why evangelical Christians hold people like Yitzhak Yosef in such high regard, while he thinks of them (literally) as farm animals and beasts of burden. I understand why evangelicals hold Israel in high regard, but I don't understand why that extends to someone like Yitzhak Yosef.
Oh well... just another day. :2 cents: