Signage is only a very small part. It isnt 600 pages about signage. Im no expert in tne area, but it is also about:
Quantities that can be transported
Classifications
What can be transported with what, due to chemical incompatability.
The type of packaging required
Signage for emergency services
Placarding
Emergency information, again for emergency services
training requirements
Transfer of dgs
Equipment requirements including references to equipment design such as lpg or fuel tankers.
Cootes disaster was mainly caused by poor maintenance. Two died and 5 injured. 525k fine.
There have been incidents in the 1800s and early 1900s that killed thousands, and even plenty of close calls, even recently in australia.
The dg code is complex for a very good reason. And for one Im glad we have it. To see the alternative just google disasters in usa or any 3rd world country you would like to pick