The Paris metro system is free for under age four, and also for residents sixty-five and older who have a reduced income.
I feel your pain, Bryan. There are lots of transportation options here in Paris, but you never know when something is going to go haywire and possibly ruin your day. I thought Friday was the day from hell, with late buses having to detour around certain neighborhoods, closed because of 1) a gas leak, and 2) a demonstration. Plus, the automatic line #1 trains ceased to stop in my nearby station for some odd reason. However, on Saturday, a very petite older woman, getting off the bus in front of me, had the doors slammed on her, squeezing her shoulders and arms. It looked awful, but she didn't seem to be harmed and just shook it off. The driver appeared to be more upset than the woman.