this seems very bizarre to an american reader, where we have the terminable at will doctrine.  i have been an employer for 20 years of a small business, and perhaps 40 people have either quit or been fired.  all of them, every one,(except for a few deaths), is working and in a job at least as good, often better.  the system only works, of course, where there are many jobs available.  and the kind of restriction you favor does seem odd to us.  no one hires someone and takes the time and effort to train them unless one is hopeful that it will work out and that the relationship will be mutually beneficial. but that sometimes is not the case. sometimes it does not work, and always firing the person is better for everyone.  similarly, sometimes business turns bad, and one needs to cut to protect the jobs of the others. Employers are not looking for excuses to fire, but for reasons to hire.  The french system has it backwards.