As long as all guild members are treated as equals, it is possible to divide loot fairly over time.
You can go "round robin." Suppose a bard item drops. All 4 bards roll and Bard 1 wins the item. Next bard item, the other 3 bards roll and Bard 2 gets an item. Next item, the remaining 2 bards roll; and the 4th item goes to the remaining bard. After that, all 4 /random again, and so on. Or, even better, carry on in the same order. That allows you to continue the even distribution across raids. If Bard 3 doesn't show up to the next raid, he or she gets skipped.
If you show up for more raids, you get to roll more; and over time, you get more loot. If you roll unlucky for long enough, you still eventually get loot, as others will no longer need the items that drop.
Another alternative:
the Suicide Kings system.