Why is the secondary injector circuit so complicated?

[Matt B]

Recently I grabbed a beer and studied some wiring diagrams of my ZR. Just out of curiosity...
Looking at the fuel delivery section a question came to my beer-drenched mind: why did they do it that way?!?

My point is: each primary injector is controlled directly and individually by the ECM.
In the secondary path two injectors are controlled as a pair and ultimately energized by one of the two well known secondary injector relays.

To my limited understanding this doesn't make any sense...
I thought about a potentially higher energy demand for the secondary path. The FSM says that in full power mode the fuel delivery is equally split between both injectors. Also technically primary and secondary injectors seem to be identical. So, a higher energy demand can't be the reason to add a relay - which potentially may fail one day...

Does anybody know why GM/Lotus didn't apply a direct (no relay) and individual control to each secondary injector but chose the two-as-a-group and relay layout?