Actually, German railways is experimenting with airline-like ticketing systems (called surf & rail), where they sell discount tickets with restrictions
- 7 days in advance booking
- tickets are non-transferable
- tickets are non-refundable and
non-changeable
- saturday night stay required
- no discounts for kids
- no liability whatsoever

...sounds familiar? Current rail tickets in Germany are equivalent to full-fare coach/biz tickets without a seat assignment (extra fee for that), so this is a logical business move for German rail.

I'm waiting for voluntary denied boarding on the S-Bahn Dortmund-Wuppertal, status-based "up"grades (sorry, coach is overbooked, would you mind standing in the aisle?)

But maybe the airlines pick up the concept of the BahnCard (50% discount for 12 months if you purchase the card for about 110 USD) and the season-pass (how much would a one-month pass FRA-SFO cost? ).