My local municipality decided that it would be more appropriate for lights to flash yellow and/or red on a couple of low-traffic intersections along major routes between 11 PM and 6 AM.
I have a few intersections near me that desperately needed to have the lights added but only for busy times of day. At night it can take 5 minutes to get through a battery of lights even with virtually no traffic.
I suspect choosing not to flash them at night is some combination of people not really familiar with that system getting potentially confused and (these are somewhat complex intersections) others just getting careless rather than carefully checking, at night, all the directions that traffic could be coming from.
That is the beauty of roundabouts, they work regardless of the time of day, and on some where there is a need for more regulation you can still add lights before the roundabout.
I suspect choosing not to flash them at night is some combination of people not really familiar with that system getting potentially confused and (these are somewhat complex intersections) others just getting careless rather than carefully checking, at night, all the directions that traffic could be coming from.