Don't lawyers have effective ways to include and reference things, create standard definitions and procedures without pasting the same stuff everywhere?
In some fields, yes — but as a class, lawyers: (A) notoriously prefer reinventing the wheel, and (B) sometimes could be suspected of hoping that the MEGO Factor — Mine Eyes Glaze Over — will cause the other side's contract-draft reviewer to overlook something that the drafter buried in a long, wall-of-words provision. I see that happen pretty regularly.
(In the 1990s I initiated and headed up a project for the American Bar Association Section of IP Law to try to standardize the wording of various building-block clauses for software license agreements. [0] The chief IP counsel of a Fortune X company [X being a very-low number], whom I knew pretty well from the Section, said he was opposed to having any kind of standardized language because, he said (paraphrasing), "I want to be free to be an asshole.")
[0] https://www.oncontracts.com/docs/Rutgers-MSLP-Precursor-to-G...
That could actually turn out to be worse. Take a look at a lot of federal bills. They're written like:
'In 8 USC 552(b)(ii) strike the word "foo" and insert "bar baz"'
You then have to go cross reference everything for every line. It's a nightmare. If the bill was written in a computer readable diff format instead, that could be better.
I no longer work in law ;)