I'm guessing you've never had a back injury.
Unfortunately, I've had back issues the last few years due to bulging discs (mostly from lifting) that have rendered me useless at times, but fortunately with time and therapy my back is on the mend, but will never be the same....according to the MRI.
A back injury can definitely be a serious injury, and can be very painful and debilitating. It all depends which area of the spine has been damaged and to what extent. Muscular back injuries can be very painful and debilitating too, although they tend to be less serious and usually heal faster than a spinal injury depending on the extent of the injury.