OK my experience.
My principal instructor asked Hombu what the procedure was and from my end it went something like this.
I had to send my Aikido CV to the Hombu dojo. During the next year a Hombu Shihan observed me teach (at Summer School) and sit on a grading panel (up to Sandan). I then got a nice certificate and letter following the next Kigami Biraki ceremony.
So I guess there is some kind of quality control. As I see it if you join the club (Hombu) then you play by the rules.
You and I share a common background.You will remember the days when you could have been a Ist kyu for a million years[or so it seemed]..Even when you went for testing in the case of a certain shihan , you could be asked to show more waza than even O Sensei could do.The long 40 mins test.
Now I think we both agree that certain standards should be maintained.It would also suggest to me that the mindset of the group you are in does have some bearing here.It would appear that your Principal,used common sense , influence and in due course you and the other guys received
your Shihan title.Obviously , your principal felt you merited the award.You had the opportunity, you gave your cv, you tested,You were deemed competent, and you received the Certification,
Just goes to show your Principal is more forward thinking than some. I do hope you and your family are well,Please let them know we [Jenny/myself ] send our best regards, Cheers, Joe.