First thing - some people really do need surgery, and for many people, surgery can have a profound impact on someone's function and quality of life. This post is not intended to call that into question or to imply that these individuals haven't tried hard enough before going under the knife.
I'll post my thoughts on injections later. Let's talk surgery. Surgery is great for traumatic injuries-- especially when it comes to putting broken bones back together. For an ACL tear, surgery can be critical as well, although this idea is being called into question recently as some athletes have made full recoveries from this kind of injury without surgery. Those with advanced knee and hip osteoarthritis have had their lives changed by joint replacement surgery.
When does surgery not seem to work well? In cases of chronic pain, where there is only mild to moderate degeneration present, most studies have found surgery to be no more effective than placebo. I'm looking at you, spinal fusion surgery. I have seen many patients who have gone for surgery in the hopes of curing their pain, only to have the pain persist, and once you go into something with a knife, you can't take it back.
In the case of pain and injury, we really like to overcomplicate things when often the best solution is actually the simplest. Just like a healthy plant needs rich soil, sunshine, and adequate water to grow, we need good nutrition, plenty of sleep, and a good handle on our stress to heal and feel better. Throw in some movement and exercise, gradually progressed as you get stronger and can tolerate more, and for the majority of people, magic happens.
So many skip this step and jump to the more aggressive option, such as surgery, before really giving these basics a fair chance. Healing takes time. The tallest, hardest wood trees-- like oak vs. bamboo-- take the longest to grow, and our bodies are much the same that way. Never underestimate your body's natural capacity for healing and recovery.