"This guys is not the best I could find, he doensn't give 120%" is a perfectly good reason to fire someone. What other reason could there be? that he or she stole the coffee machine ?
What maz-dev does not tell is that even if an employee steals the coffee machine, you will have a very hard time firing him. I will cost you a lot upfront and the employee will most probably win in court so you will have to pay him even more.
This is by far France's biggest problem. I had the "privilege" to tell that to our president Hollande, and he just confirmed he does not even understand what's wrong with that.
If someone steals a coffee machine, first get a proof. Then you need to set up two meetings before firing the employee. Once this step is done, you send him or her a letter and he/she's officialy fired.
The employee can then request a reexamination in front of a court (prud'hommes). If you have any proof it will cost you 0€, you don't need a lawyer when going on prud'hommes and this will take you max 1 hour of your time. You can then ask some money to the employee to cover the damage caused and the time lost.
If you don't have any proof, then yep, you're fucked, and for a reason "presumption of innocence".
Cool for you to meet M. Hollande, but I'm afraid his role is not to vote laws or change the labor code, other instances less centralized are already dealing with this.
That could be a reason. You could also agree on clear goals with the employee and fire him if goals are not met. No problem. Just take the time to agree on clear, written, and official goals with him. You can fire him if you're in a difficult situation financialy speaking. But you have to prove this.
Not being an overachiever is by no mean a reason to be fired, not in France.
Things are changing slowly though, new types of contracts are being voted. They should bring "Flexibility". Give France a few years and you will be able to fire someone just because he's wearing a yellow shirt.
Given the mindset of french workers and unions, this new type of contract should actualy lower the overall productivity.