ESA letters

This is a part rant and part question but...

WHY WONT ANYONE DO AN ESA LETTER!??!?!? I've seen two different therapists in the past 3 years and none of them will do it. Why??? They all agree that I have a moderate-severe mental health condition and that my cat provides emotional support. I've even had one of them let me write down that my cat is apart of my support network. My cat is my world and very important to me.

However when it comes to writing a letter about it? They all scatter like mice when the lights are on. I'm so confused on what it's a big deal. I am wanting the letter so I have a little bit of legal protections when it comes to possible renting in the future.

((I wanna note that I am specifically talking about an ESA and not a service animal))