The dynamics of risk change with the size of the entity involved. For example, in a small startup, losing a hard drive could mean the end of months of work - could kill the company. Or since everyone makes backups / uses hosted services these days ( right? ;) ), maybe a better analogy would be an employee being lost to sickness for months.
In a 100+ person company a broken hard drive should never be anything more than annoying, losing an employee is going to be unfortunate and might even significantly delay a product/feature; but it won't be the end of the business.
There's a raft of interpersonal dynamics which change too; the larger the company the less likely you are to be pally with everyone. Simple factor of surface area - you can't cover them all. So relationships become more formal. As spheres of responsibility begin to form, people develop moats around those responsibilities for better "separation of concerns".
At some point I suppose stuff starts to slip between those self-defined spheres, especially as people move in and out of roles, subtly redefining them each time. Making sure you're not being negligent (or seen to be negligent) in a multi-million dollar company is kind of a big deal if you expect to work somewhere else in future (and especially if you intend to keep working at that company).