It is not usually the fault of these instrumentalists that their instruments are loud, or that composers ask them to play fortissimo and beyond (wagner, strauss...), and it is often your job to seek out shields or earplugs in those situations, and hope that the conductor will manage volumes when appropriate. In addition, it's important to be clear with management about the importance of shells for protection. Some of the orchestras I've played with did not provide protection, and while I often have my earplugs in my case, many others don't. If you are a sub or extra musician, always bring your own plugs. It can be stressful to tell personnel managers about the sound situation, especially if it's a high profile concert or conductor. Your long term hearing is more valuable than your ability to play fast passages in a Wagner overture, Mahler symphony, contemporary piece, or Pops show. If you can't hear yourself over the cacophony, chances are, your stand partner can't either, nor can the section leader or concertmaster. (Not to say that preparation is optional, but sometimes folks are afraid to use earplugs lest they play wrongly or out of tune). Prepare well and also experiment with knowing your own volume with and without earplugs so that you can start to be more comfortable using them. Many of my colleagues have found most success by using one earplug and leaving the other ear open directly next to the instrument, although there's certainly a case for mixing it up to prevent long term asymmetry.
If you are a youth orchestra coach/leader/teacher, check out the situation in your class or ensemble. Many teenagers are not apt to worry about hearing loss, and your assistance could make a big difference. Also, avoid always use in-ear headphones, which are more damaging long term to your hearing depending on the frequency and volume of music/sound listened to.
One last excellent point that my friend trombonist Chris Wolf pointed out to me, is that many musicians deal with something called the occlusion effect when earplugs are in, meaning that the sounds are perceived as booming, and difficult to perceive in context. Many of my friends who don't use earplugs say that they can't hear their section or intonation well, but just can hear their breath (especially wind players). It seems as though hearing specialists have addressed this issue in the context of hearing aids, but I wonder if it's something that audiologists are looking at for musicians, especially those who play wind instruments. If any of you have any experience with resolving this issue or know of a brand of earplug that addresses this, let me know!