It is fair because you don't see what fairness actually means.
1. The seasonals are the same for eveybody, on every console, on every GT5 version.
2. The AI does always drive about the same total times, really small differences.
3. The AI doesn't really do random stuff, they drive extremely consistant
4. PD doesn't give us the statistics, but I'm sure at least a few thousand people do golden these seasonal events regularly.
5. If others can do the very same thing but you can't, whos fault is this? PDs or yours?
6. It's a damn challenge and by participating you indirectly accept that challenge and try to win it.
7. It's a game.
8. Why do that many people seriously expect to have the ability to always finish a game to 100%? WHY???
9. A game has a wide userbase, it must be attractive for everybody, including the very good players.
10. If you can't get gold then you can't get gold ffs. DEAL WITH IT!
It's not as if as example a F1 champion would win every single race or always start from pole or similar. As long as that many people can golden these events, it's nothing wrong with it.
11. It's not as if you wouldn't get any money for second place or worse.
12. GT5 has some more and some less difficult events, stick with the easier ones if you can't accept to lose.
13. You better go and sell GT5 before anything bad happens.