There are so many widely open train stations in France that securing only some of them would be a huge waste of time and energy while securing them all would be nearly impossible.

And I really don’t want to live in a country where boarding a train is as painful as boarding a plane. Millions of people are using train to commute, adding security checks would totally kill the train.

For what’s it’s worth it’s more of a bag scan rather than a full security check like at the airport. Certainly the full security check is not something I want to deal with but it wasn’t too bad. They only do it at the main stations in Spain and only if you’re riding the high speed trains, so I imagine if France did it then it would only be at TGV stops which are not so numerous