Road bikes don't do dirt. Thats why i don't do road bikes.
Dog walkers don't like road bikes blasting by at 30+ MPH. And road bikers training don't want to tangled up in that mess. It is inevitable, when you come up on someone on a trail and yell coming up on your right. 95% of people demonstrate they have no idea which is left or right, and you never quite know what they are going to do. Kind of like a squirrel in the middle of the road.
A lot of people on bikes are commuting or at least headed somewhere specific. This means using roads to at least get to the trail, and off the trail to your destination.
Why everyone thinks they are so fucking important they can't be slowed down by traffic for 30 seconds if its a bike is beyond me. Half of the same peole complaining have probably sat in grid lock for hours because of other cars. And half of those lazy fucks are probably with in easy walking or biking distance of their destination. I had a friend telling me about his 10 mile 2 hour commute. Made me laugh, I can damn near walk 10 miles in 2 hours at an average pace.
Saving the environment,
My bike saves me time and money. It paid for itself with gas money saved commuting in its first year. Headed to the back country to see the dino tracks. Ok, I will be there taking a nap when all you tired dusty fuckers come walking up.
I was looking for an article about the trucker here in town that ran over a vietnam vet, tried to narrowly miss him by passing him in his lane, and dude crashed under the truck when he went by so close. I am pretty sure he was looking at time in pokey also.