Would you say this is fair?

[Mollzz]

I applied for an internal position but was not invited to interview, despite meeting all of the essential criteria (though not all of the desirable ones). A colleague was selected for the role. They've already received funded training for 6 years and will be close to 80 by the time this is completed.
I also believe that no other candidates were interviewed apart from them, as there were only three of us who applied. In addition, the job vacancy was amended in a way that seemed to align more closely with their profile. For example, the training/study requirement was originally listed as essential but was later changed to desirable, along with other criteria.
I’m not entirely sure how to feel about this. I’ve expressed interest in progression for a long time, but so far it hasn’t really been facilitated.

Well you could ask about the interview/ selection process but I would be tempted to look elsewhere, it doesn’t sound like the company recognise your skills

Whilst I agree with @Gizlotsmum that it does sound like your options lie elsewhere, have you actually asked for feedback? I say that because I have often had staff tell me that they are shocked they didn't get an interview since they met all the essential criteria - except for the fact that I was part of the interview panel and I know they didn't! When I have pointed that out in feedback, they have realised that they have actually not met all the criteria - they often could have met them, but on paper they failed to say something that we needed them to say to meet the criteria.

Their age is not really relevant - discrimination on the basis of age is unlawful. That said, if anything what you describe does not make logical sense from the employers point of view. I might have expected someone still working in their 70's to not get a role, especially one with a 6 year training period. If this person is that valuable as an employee that an employer would go out of their way to make sure they detailed the JD around them, and risk a wasted substantial investment in training, then they must be very, very good. Or have some amazing dirt on the employers.Unusual though this situation is, fair or not I would have expected quite the opposite - someone of that age being not considered for progression / investment.

In the end there is nothing you can do about it though.

No, they’re not very good. They’ve had complaints and can’t deal with certain types of clients and activities anymore. They’ve been there 10 years, and I’ve also heard from other colleagues about other issues where they found them rude and racist but didn’t want to escalate it.
They meet most, if not all, of the desirable criteria, so there was no reason to reject them. They weren’t eligible for the funded training either, but they escalated the matter to HR because the policy encourages growth and development so they made an exception for them.
Anyway, I’ll just focus on making myself a stronger candidate for future positions.

I'm then going to go with they must have some damning photo's of the boss 😀

I’d be seeking a job elsewhere.

Do you have the training they are on? If not I would. Make sure I get on it

I don’t have the training they are on at the moment, but I plan on doing it next year once I’ve saved for it, as it’s no longer funded. They were the only ones to receive the funding.

An old boss of mine once said about somebody that they had been "promoted out of harm's way" and at the time I didn't understand what he meant!