Someone answered that quite eloquently on another thread. Anyone can make a mistake - except Jamie2k9 perhaps. What about people who are old and not computer savvy, or simply don't have access to a computer and printer whilst on holiday? What about people who lose their documents (or they are eaten by the dog!) or just got wet in the rain?
You're in favour of 'fining' people or making them pay punitive charges for their mistakes. That sums up the attitude of Ryanair and is precisely why so many people refuse to travel with them.
Everyone can makes mistakes but some mistakes are more costly. Don't use *old people" as an excuse, if they can't use a computer who booked the flights, the person who booked them should of printed them out. Not have access to a computer on holidays just doesn't happen. Majority hotel has computers and internet cafes are all over the main areas. Your using excuses and I don't even need to give an answer to the rain excuse.
I expect if FR released the stats for people who forget to do it, a certain profile of passenger/s would be a regular occurrence. We are talking at most a couple of thousand out of 80 million passengers. It does not happen very often.