Are fixed damage weapons worse than damage range weapons?

When sorting weapons by damage in Fallout: Shelter, weapons that have a damage range (as the Enhanced Sawed-Off Shotgun, which does 6-8 damage) are ranked higher than fixed damage weapons with the same expected average damage (such as the Rusty Laser Pistol, which deals 7 damage) when sorted by the STATS column.

For example, I currently have the following weapons in this order when sorted by stats:

Enhanced Sawed-Off Shotgun: 6-8

Rusty Laser Pistol: 7

Sawed-Off Shotgun: 6-7

Enhanced Hunting Rifle: 5-7

Rusty Sawed-Off Shotgun: 6

This could be as simple as the sorting algorithm just being made that way (sorting by average damage first, and then maximum damage to settle ties), but I would argue that fixed damage weapons are actually better (given the same average damage), as they would bring more consistent victories in situations where you on average win.

I considered that the random number picked within the damage range would be affected by the dweller's stats (so having high perception, for example, could increase the average damage slightly for a non-fixed weapon), but this seems unlikely, considering the simplicity of the FO:S combat system.

Is this purely an artifact of the sorting algorithm, or is there some reason for why damage range weapons are (on average) better than fixed-damage ones?