When is a public holiday not a public holiday?

when the trains are on strike.
I have a choice of 3 different ways to get to work (outside of walking 6 km) using the public transport system. I like to mix it up a bit, to keep my brain mildly occupied with the thought that each time I probably should've chosen one of the OTHER two that morning. My most common is the RER, an interregional rail system that extends a good distance to the surrounding ile-de-france areas. I can generally get a seat (though, sometimes it's puzzlingly packed to the doors, and I have not yet identified the causes of these random fluctuations) and its a lot nicer than the bus or metro which are generally like a tin of sardines - packed to the brim, and funny smelling.
Yesterday they announced there would be strikes today with only 1 in 4 trains running (though sometimes I suspect that's all they have even when they're not on strike)so I decided to take the bus, of which there were 3 lined up at the stop when I arrived (preparedness, good!) but there was practically nobody on the bus, on any of them. I arrived at work 10 minutes early altogether puzzled at how my little imagined nightmare turned out to be one of the more tranquil commutes I've experienced. It turns out that most people, when a strike is announced, just take a day off (everyone seems to have a luxurious amount of time in lieu because most people work more than what is now the standard 35 hour week). Vive la France.