This excludes US based groups lobbying for Israeli interests, which does not count under official spending by Israel, so it is not an accurate representation of the lobbying effort in the interests of Israel.
This is a reference to Americans. Americans choosing to freely donate to groups/causes they support and Americans being involved in American politics.
That seems like the categorically correct thing to do, for the same reason that (for example) a domestic Korean-American nonprofit that lobbies for Korean interests doesn’t get counted as foreign money or influence.
(Perhaps it should be! But it should be consistent, whatever it is.)