France is a much smaller country. When there is a mass protest in the US, it ends of being a bunch of smaller protests all over the country, which lacks the power of a single concentrated protest. These various satellite protests just end up being a minor nuisance, which don’t amount to much.

The media in the US often ignores the protests they (or their owners) don’t agree with. This also weakens them significantly. I remember having to go to Twitter to see what was going on with a lot of the Occupy Wall Street stuff, because the news was acting like it wasn’t going on. Without attention, and fractured across the country, it faded out. The protest area where I was living at the time slowly shifted into a homeless encampment, before they eventually cleared them out.