Okay, I'll bite. Where does this rule quote come from. I skimmed both the 5e PHB and XGTE, but couldn't find it... actually, digs around in old stuff
Oh wonderful, you have once again quoted 3.5.
3.5 rules do not apply to fifth edition. They never have, they never will. 3.5 was two editions ago. It does not apply.
Here are the fifth edition rules. I'll highlight and discuss.
1) This tells us what we are talking about. Copying spells, from any source, into a spellbook. Unless stated elsewhere, if you find a wizard spell you can copy, it will follow these rules. You find a stone tablet inscribed with the spell formula, you use these rules to copy it. You find a mystic scroll with the spell formula, you use these rules to copy it. You find an enemy spellbook, you use these rules to copy it. This is further laid out by the first sentence, which literally says " When you find a wizard spell... you can add it to your spellbook
2) This further breaks down what is going on. To copy the spell, you need to remake the basic form, the formula if you will, and practice it. Additionally, you need to "decipher the unique system of notation used by the wizard who wrote it." This tells us that wherever you are copying this wizard spell from, it was written by a different wizard. This includes if it was written in their spellbook. So, this is directly stating these are the rules that you follow to scribe a spell from one spellbook into another, but maybe that doesn't convince you. After all, how do I know this "unique notation" applies to spellbooks?
3) Oh, it says it right here. You write spells in your spellbook using your own notation system. A unique system that if another wizard wanted to figure out, they would need to decipher, just like it said.
4) Which makes these rules, 50 gold and 2 hours per level of the spell, the cost of scribing a spell from one spellbook into the other. There is no "Access" fee that a wizard might charge you, this is literally the only cost. If you have a spell book and want to scribe the spells in it into your own book, it costs 50 gold and 2 hours.
5) This only strengthens what I am saying, because it is easier and cheaper to copy your own notes than to break down a spell you do not know and decipher the foreign code. Because the 50 gold and 2 hours is for scribing a spell from a different source (scroll, tablet, spellbook, knotted rope, doesn't matter) into your spellbook.
I literally can not get any more clear than this. These are the rules you insist do not exist, and it seems that your issue is that you are seeing the cost as being the same as some rules from 3.5 and are assuming that those rules must be applying to a different aspect of the game, because if it were the rules they say they are, it would have the cost from 3.5.
3.5 rules do not match 5e rules. The rules for scribing an enemy spellbook are the rules quoted and bolded, that you quoted at me some time ago claiming I was mixing them up with some rules from two editions ago. I wasn't. These are the rules you are looking for.
Yes, I know.
So, in the official material, they only have the spells from those two monster statblocks, and that is somehow bad and should be the standard by which we measure all games across all tables for some reason that makes wizards bad at finding and scribing spells.
My only point was that even if WoTC runs 100 adventures and every spellbook says "It contains all the spells listed on this convenient statblock" that does not neccesarily make it worthless to the players. In fact, it changes nothing about the actual rules written.
You can scribe those books.
You can sell those books.
There are things you can do other than insist that the rules do not exist and there is nothing you can do about it.
It was a coincidence actually. The one guy has been eager to play a wizard for 2 years as we finished the campaign with his paladin. One of the new girls was comfortable playing a wizard because it was the only class she had played back home, and she was fairly new to the game (I think I am running her second or third campaign ever) and the last lady essentially picked at random.
As for WoTC's data. I know. Doesn't effect what I said about my own table or my own campaign.