Swimmers on edge lanes get affected more, and they leave the outside lanes unoccupied except for the first stage of qualifying.

From the races I saw they specifically had the edge lanes (left most, right most) empty probably for this reason. I.e. 8 out of 10 lanes are used. I think one of them did have someone in one of those lanes because one of the qualifying heats was a dead heat.

Given the other comments I must be missing something, but wouldn't it be pretty much fair? The end swimmer gets one real neighbor and one simulated (reflection) neighbor from the wall. The middle folks have two real neighbors creating chop.

Correct.