User on main site, also on meta?

Question

If a user has an account on one of the stack exchange site, I thought they had an account on it's Meta site.

This doesn't seem the case in the associated users API route for one user (that's all I've checked, because I don't know of others)

Answer 1

Users on meta sites inherit from users on main sites, but not every main site user will have a meta account.

Meta users are spun up "on demand", the trigger generally being the first time a user visits a meta site.