You see lots of 6'2"ish riders agonising over large or extra large, yet add 5 inches and suddenly you need a custom made metal horse to ride around on. Were you 7 foot I could vaguely understand.
Thank you for being so understanding - no, really. If you look at manufacturers geometry charts their outside height recommendation is 6'6" at the very best on their bigger bikes. There is almost no market for them to make bikes for the extremes of the height ranges - no profit in the numbers - so few bikes are made. It doesn't matter whether you think global or national statistics are best - bikes are not normally available for the 6'7" rider with a 40" standover.
Edit: Actually, to bring this in line with your list of custom bikes. Turner seem to make fairly short bikes, most brands XL is the same length as their 2XL.
Despite your assertations, none of my bikes are custom. They are all OTP. The Turner was the first bike I ever managed to test ride and it felt better than anything else I'd ridden - overall design and geometry make it for me.
I've been told more times than I care to remember (by people who haven't seen me and the bikes) that I don't need such big bikes. However, everyone who sees me+bike says they fit. Funny old world the internet.
Anyway - back to the little people and their teeny tiny frames on clown wheels