Certain sounds aren't counted as sound events

I have a few sounds I found on the wiki but I can't get them to play through the playsound command
Example:
block.iron.fall Isn't seen as a sound event
This is what the logs say
Identifier "minecraft:block.iron.fall" was not registered in registry "minecraft:sound_event"
This is only one example
There are so more
Why aren't they available?
How do I play them through commands??