No, they just weren't made for the German Army. H&K made them (or more correctly had them made) for sale to other people who bought guns from them. Not everyone who bought say, HK33's bought scopes.
True. Bear in mind not all of what you'll see for these are 3rd model, some are 1st and 2nd, not the final evolution of the Z24.
1) No. 2) The fact of how many there are. 3) Because they can make money that way from the unwary. They can't remove the Z24 markings but they can make a .223 marked turret cap (there never were any .223 caps, only marked 5.56) and put it on there.
Yes.
Yes. I had one for my SD, sourced from a guy in Australia who got his hands on 5-6 IIRC when they were surplus'd off by the Australian unit that had some SD's, he was able to buy them due to being connected to those folks. I seem to recall I bought more than one from him and just resold the extra's. For me the SD with it's .380 ballistics and lack of accuracy to be fulfilling that "suppressed 100m sniper" thing got old once I figured it out by actually doing it vice reading what other people who never had wrote, (that system hasn't been the best thing around for the purpose since the .300 Whisper, now known as the .300 AAC Blackout first came along in the early 90's) both my SD and the scope got sold LONG time ago. My '91 as well. The only H&K I own personally at the moment are a USP Compact 9 and a USP .45. Being in the business I tend to acquire cool guns that I own for a while and then sell when I remind myself that I'm in business and that past that I'm an End User, not a collector. It's a conversation I had to have with myself years ago when the safes were too full and "baby needed new shoes".
No problem.