There's no other path to becoming a doctor in the US. You can choose to go into a specialty with more relaxed hours, but you need to go through residency no matter what. If you want to be a doctor, you put up with it, like the generations before you. A sufficient number of residents organizing could do something about it, but (a) no one has time to organize when they're working 90 hour weeks and (b) there's a significant Stockholm syndrome effect in play.

It's worth noting that there have been several studies over the years investigating whether reduced hours produce better outcomes; they don't seem to. Shorter hours means more shift changes and patient handoffs, which is the source of more errors than tired residents. Also, keep in made that getting the same experience in a specialized field like neurosurgery with fewer hours per week would require extending the training program even further. It's already seven years beyond medical school, often with a one year fellowship after residency. Extending it another few years isn't really a viable option unless we significantly increase the autonomy and salary that residents receive.