This is a question I get asked often, so instead of re-typing on every PM I'll just post it here. Obviously this is my opinion at current time, YMMV with other units and when I'm no longer the CC the sight picture could change again in our unit. I'm speaking from our experience in New Orleans. I'm sure other units have different stories, etc, etc. Internet advice: it's worth what you paid for it.
What the guys above have said is accurate - the unit has to like you enough to take a chance on you. More than that, if the paperwork to get an ETP is 1 measure of a$$ pain, they have to like you at least 1 a$$ pain more than a similarly qualified guy that doesn't need an ETP. If you are 1 of 75 guys rushing for 3 open slots, the odds are not in your favor to get an ETP. Every wing will have a different take on it. Obviously the less applicants a unit gets, the less picky they can afford to be.
Why is being older even a big deal? It's a subject that everyone who needs a waiver suddenly thinks they are an expert on. Arguments can be made of course and there are always exceptions to the rule. However, in our case we've sought ETPs for age before; it's actually worked out exactly like guys who we've allowed to join that are pilots but not from a fighter background. They've all ended the same way - in failure. There are lots of studies about how we learn. .69 seconds of google-fu shows me this article: https://www.fastcompany.com/3045424/what-it-takes-to-change-your-brains-patterns-after-age-25 I gave it a quick glance and that's about what we've seen. Younger people just learn better. Learning to be a fighter pilot is a major shift from the way most adults think. Breaking down those barriers when they've had time to form is very difficult; and frankly it's hard enough without having to smash through those additional roadblocks to success. UPT is where the basis of learning this life starts. If the 2 year pipeline is akin to watching a child learn to walk, employing in combat is more like going to the Olympics. There's a lot of learning to do between learning to walk and putting that gold medal around your neck. And the road never ends - I've been flying the same jet for over 17 years in a row (bragging). I still learn new things. Less often than in times past but it still happens; it's harder for me now that I'm an old guy. I can't imagine trying to learn this stuff at 30+ with a family or other life choices hanging over me. I was right out of college, 23 years old and not a care in the world. It was still very difficult (not UPT - that was easy), learning the life.
Someone was on the board recently whining about how it's not fair that everyone doesn't get an interview. I actually LOL'd at that one. If you are seeking an ETP, don't be the guy whining about why no one is giving out ETPs or being upset if a unit tells you they aren't entertaining ETPs. That will result in guys like me LOL'ing at you and immediately jettisoning your resume and face from the collective memory of the hiring board. Be humble, understand that they have to take a chance on you and that the odds are not stacked in your favor. The board or unit didn't cause the circumstances that made you late in life to apply for this opportunity, you did; own it.