Regarding the current movement which started with taxes on gas, the tax raise is insignificant vs. the actual oil price increase. Read this article (in French) for more information: https://www.lemonde.fr/les-decodeurs/article/2018/11/09/peti...
Also, the people who go into the protests to break cars and shops have nothing to do with the original movement. Some clearly came to loot shops (if you are anarchist, you want to burn luxury clothing items, not take them), some are anarchists who came to fight police forces, etc.