> Some people are allergic to some type of animals though, how do you handle that?

The same way people allergic to other things handle it. They do their best to avoid it and they keep an epi-pen on themselves in case they're accidentally exposed.

I was once at the Los Angeles airport, and a fellow passenger walked up to the counter and told the person there that they have an airborne peanut allergy, and to please announce that nobody in the concourse could eat nuts. The person behind the counter did so, but realistically, this did very little. Between the vast majority of people ignoring most announcements, and the literally thousands of people per hour coming and going from other areas in the airport and planes, there was no way you could keep everyone in the area from eating peanuts. It's on the person with the allergy to make sure they can safely go wherever they're going. You can't expect the rest of the world to magically know, or comply with procedures for your particular issues.

Yes its basically a scam with people taking advantage... As the saying goes the road to hell is paved with good intentions... I think flyertalk has people complaining about the ease with which you can get the cert

It's a per seat thing. It's not like someone in dire need has no room for their animal becomes mine is under my seat! Also, I have a hypo-allegenic dog, but they'll reseat complainers. Usually though I have the opposite issue. Everyone wants to touch the dog etc.