France now has ~ 12% Muslim population. Many of them came from Algeria (since Algeria was a French colony).
So consider the lawless ness and hooliganism resorted to, to celebrate New Year.
The "terrorism" word is derived from terror.
Terrorism is the systematic use of terror especially as a means of coercion.
The Merriam Webster dictionary defines terror thus:
1: a state of intense fear
2a: one that inspires fear : scourge
b: a frightening aspect
c: a cause of anxiety : worry
d: an appalling person or thing ; especially : brat
3: reign of terror
4: violent or destructive acts (as bombing) committed by groups in order to intimidate a population or government into granting their demands
The French government too, like the Indian one, has been taking kid gloved approach to the issue.
They (like successive Indian governments) believe that if you bend enough, Jehadis will be happy. Same factors are working there. Liberals with no clue about political Islam and socialists look at such incidents as those of "misguided youth" with "grievances". So it is OK if you are "misguided youth" to burn public property and indulge in arson.
We know how this works. Imagined wrongs from past will be dug up, One Babri Demolition will be sung millions of times, thousands of Hindu temples broken will be airbrushed from history and public memory.