Not that I am complaining or anything, BUT:

It's time to kvetch about France, Paris and the French. No visit here would be complete without a certain degree of exasperation, nes't pas?
Par example: There is always an extra bureaucratic step to everything. Free events are free, which is a wonderful thing. BUT. You still need to get a ticket for the free event. You still need to do the bureaucratic dance. Ces't comme ça.
More annoying: There is a mystery as to what metro ticket vending machines accept working credit cards. Some do, some don't and it's all very mystifying. Some machines only want cards with chips, others are more ecumenical. Seems that the more touristy the area, the more benevolent the machines.
BUT. Would it kill the Metro to have a machine that accepts bills, not only coins, and cards with and without chips? Would it kill the Metro to issue easy, convenient things like NY's Metrocards instead of annoying carnets of 10 loose tickets or a Navigo pass that requires your picture and the signature of Cardinal Richelieu?
It is the height of convenience to buy your train tickets online and just print them out in a machine at the station. In the very possible case that the machine does not accept your card, happily, you can also type in your confirmation number, BUT after you do so, it still asks you FOR THE FREAKING CARD IT WON'T ACCEPT.
So in the end you have to do everything analog anyway, like in the Ancien Regime.