Bolting is an ethical issue that is discussed at length in the climbing community. The ethics are very strong in Yosemite and therefore there are almost no bolts and all the climbs are done using removable gear. (also called trad gear). I'm also baffled that you compared a couple micro pieces of metal to the disruption that a road provides to the environment. Or even compared to skiing resorts, mountain bike trails etc. In my experience climbers are some of the most ecologically respectful people out there.