My mother told me when I was young not to jump from a skyscraper just because others did so.
I for one would never feel that it would be against my honour or friendship not to jump.


Look at it this way; some armies have fought campaigns with great displays of courage, others not so. It's not necessarily the honour of the soldiers, their volunteering before the war etc that makes the difference. Sometimes it's simply their judgement that taking such risks would be stupid. In fact, it might even be stupid from the society's perspective, for a 25 y.o. has hardly paid back all the upbringing and education he got from the society already.
To die in a stupid conflict that serves no purpose means he'll never repay his debt to society (for his sacrifice would be of no use*).


Finally, there's more than survival motives that can keep one away from accepting deployment. They may have bonded more with their family than with expeditionary warfare, or they may expect to do useless harm to foreigners if deployed. You know, some people actually anticipate that #### happens in war and don't want to risk becoming a bad guy for a cause that's not worth the risk.


*: This appears to be a wide-spread difference to world war-time attitudes.