Imagine being required by law to follow specs you have to pay to know.

Relevant case law:

• Georgia v. Public.Resource.Org, Inc.
• Veeck v. Southern Building Code Congress Int'l

TL;DR: once "annotations" or "model codes" or whatever are incorporated into the actual law, they are no longer eligible for copyright.

That doesn't stop organizations like SAE and ISO from trying to bully and trick you into agreeing to pay them for copies that you obtain directly from them instead of trudging down to the local law library and making copies yourself, however. (And it's even worse when you want convenient electronic copies instead of paper, because then they try to apply EULA bullshit, which I've already debunked in another comment.) IMO it's probably best to get the documents from some third-party source so you never get on the standards org's radar for a shakedown to begin with.