I agree with your corrections, to an extent. However, it is also important to note that an H1B holder is limited in the kind of jobs he or she can take. An H1B holder would have a very difficult time changing fields or entering a very different kind of employment. Becoming a private consultant, or leaving the tech field for other, perhaps better, opportunities is not really an option.

So while I certainly agree with you that "they cannot change job" is inaccurate I also believe the statement "you are free to leave to another job" is misleading. You have some very limited mobility rights, but nothing approaching what a free member of the labor market would have (sadly, this is a big part of the appeal of these visas to many employers).