Is this an attempt to keep the meat entering Israel kashrut or is there some other kind of motivation for these laws?
Not sure but I think that all or many countries do this to each other. Especially products coming into the U.S.A. I think its precautions and other things to make sure that their isn't infections and such. As I understand its usually easy to take out of the U.S. and hard to into the U.S.
Also besides these "official" things their could also be about tariffs and about lowering competition. I saw someone being caught trying to take a chicken into the U.S. from some South American country, also someone else with packs and pacts of cigarettes being stopped, they scanned it, videotaped him and then took him someplace else. I also got "busted" in the U.S. airport because I was stupid enough not to notice an apple that was in my bag. They took it and said I can go.
-- You need to report every food you bring in to customs I guess. On the airplane they give you a paper with the foods your bringing in, you need to write everything down and its value as well.