If I pick you up in my car you can tell me where you need to go, if you need to stop for food, etc. and I'll take you there. By your logic I should also let you sit on my lap and steer?
You're comparing a real life example to an aspect in a fantasy game.
All I was stating is that since the dragon is technically under your mind control (bend will), controlling his movements should not really be all too far out of the question. He already obeys your commands, so technically there is no reason why you shouldn't be able too "control" him as you pretty much already are.
There is no bend will shout in real life, so the car example does not really apply.
I'm pretty sure it just comes down to technical issues and/or laziness as far as controlling the dragon goes, not the fact that he's a dragon and doesn't want to be "controlled" by some human.
If that were the case they would've left out dragon riding altogether. The main logical argument is the game wasn't designed for flying mounts and with console processor it would likely cause crashes.
Bottom line: Either they were restricted by the game/hardware, or they just didn't want to take the time to get it to work properly. It has nothing to do with the fact of the dragon not wanting to let someone control him.
We trained harder than you today, and we're gonna party harder than you tonight. Mint with the crew.