Side note: It is depressing that the question winds up being asked this way (EDIT: while ignoring how depressing it is that it is an existing question in the first place) !
Instead it should be: "Is it generally easy for employers to get permission from their employees to be assigned all rights for code they write in private?"
This is just as depressing. Employers should have zero rights to code their employees write on their own time unless the employee is using employer specific IP / resources or creating a direct competitor. Needing to get permission should not even be a thing.
Instead it should be: "Is it generally easy for employers to get permission from their employees to be assigned all rights for code they write in private?"