It's g cause people take advantage of "service animals" you can buy vests for them online without any proof that they actually are a certified trained animal.

I think too all you need is a note from your doctor saying you need a service or support animal. I don't think the doctor has to know if they are trained for it or if they are well behaved enough to be in public places as one. So people often do that as an excuse to bring their pet anywhere.

Imo unless you absolutely 100% have to fly with your animal then find someone to watch them while you are gone. I can understand people that actually do need them not wanting them with cargo if it's not temperature controlled and can be dangerous if it's too hot or cold.