I wonder why the hoods are not cylinders.

you mean tunnels. Both were offered. The signal is programmable so its not really necessary to have tunnel visors.

These look way better than tunnel visors anyways. The cutaway visors have more character to them.

They do, my area is nearly completely cutaway but there are a few tunnels scattered around the city.

We're all tunnel. Tunnel visors don't look bad on newer signals, but on the older ones cutaway is the only way to go IMO.

it's very mixed here....in fact I have seen some traffic lights with both....(IE...replacement visor....with tunnels on red yellow...but visor on green....or vice versa and all the POSSIBILITIES you could think of!)

Tunnels on red and yellow, with cutaway on the green is a standard some municipalities use so pedestrians can see the green light. Kentucky puts cutaways on the red and green, and tunnel on the yellow, so pedestrians can see both red and green.

Intelights don't need tunnels since they're digitally programmable.