Base jumping is not allowed at Yosemite but people defy the rules with regularity. Yosemite has a great many places wing suiters and base jumpers can leap from and none of them have 24 hour guards to prevent those activities.
Although we have rules and laws the vast majority of them depend on people to voluntarily obey them, removing the need to physically enforce them. When people choose to violate a rule or law there can be natural consequences that far exceed what a court would impose. Such is often the case with thrill seekers and risk takers. Some will never learn their limitations, achieving them in a manner that prevents them from realizing they were exceeded.