I can't speak for Halal but in Israel Kosher is considered a scam by quite a few people. The idea that Kosher is given by a private entity isn't exactly correct. It's a rabbinical institute, not a private business. Their incentives are problematic.

In order to get a Kosher stamp you need an "observer" who is some guy you pay to hang around and make sure you do everything right. Sometimes the guy is actually helpful, but usually it's just some nephew of the Rabbi who hands out the kosher certificate.

Their main focus is to keep you purchasing only other products deemed kosher. Not the quality of the food or even cleanliness. If you annoy the wrong people you can lose your certificate and essentially get black listed. You can't open on a Saturday etc.

I used to joke that the easiest way to gauge the quality of the restaurant is in an inverse proportion to the size of its kosher sign. Most restaurants in Tel Aviv (excluding, Humus, Falafel or Shuwarma places) are not kosher.