Well the seats were just wooden in second class. Common in Europe, the old Berlin S-Bahn trains were the same. I seem to remember the Paris Metro ones in first class did have some padding. Paris must have been the last major urban transit system to retain first and second class, until the 1990s, the first was normally the centre car of the train and the cars were painted a different colour - the old trains were utility green for most cars, and the first class were red. The newer trains were pale blue with cream stripes, the firsts were the reverse, cream with pale blue stripes. Composites were actually painted half and half in each colour scheme. An overhead sign on each platform indicated where the first class car stopped.With brutal hard seating as I vaguely recall ...."basic" units to say the least.
The Paris Visitor weekly ticket gave first class as a matter of course. I never had a ticket examination in there.