Generally they do. When you bought your stock, they must have come with a document outlining what are your rights within that company. Best try to find it and see what it says.
In practice, some comply to the rules and some others don't.
Unrelated to your comment here but a while back you mentioned you liked some Space Cadet keycaps I had, but they are usually only available via a group buy. There's another one going on right now for a set that looks the same but comes in a different key profile: https://geekhack.org/index.php?topic=105375.0
In practice, some comply to the rules and some others don't.