removed
Problems such as that do routinely happen with stop signs, which is why stop and yield signs are routinely replaced with traffic lights when traffic counts increase.
Also, vic.aus (where I live) recently conducted an analysis of ‘turn on red’. Which, of course, everybody would like, because waiting at an empty intersection is just as irritating here as it is in any other country. But they decided not to go ahead with it, because the economic benefit was calculated as negative, and the political fallout of the projected increase in road fatalities was greater than the projected political benefit of less-irritating traffic control.
The main effect of speed bumps is to encourage cars to take alternate routes. They are also surprisingly ineffective in forcing cars to slow down, because some drivers eventually learn that they are less bumpy taken at speed. This leads to a messy situation where some cars are trying to go slow, and some cars are trying to go fast.
Local governments do all kinds of stupid things, often under pressure from developers or residents, so sometimes speed bumps are put in and people /pretend/ that they are to slow down traffic, or /pretend/ that they think that will be the effect.
Sure they can do this.
But at the same time, they have to scale down the penalty for hitting a cyclist. Make running one over and killing him a misdemeanor, and just maiming the cyclist should result in the cyclist paying you for damage to your car.
Translation: bad, bad, BAD idea.
Cyclists, especially at night, are too dang close to invisible already, allowing them to ignore road rules would just further endanger them.
As for the original question about traffic lights:
Hereabouts, manyf traffic lights will revert to stopsigns after-hours. Sometimes even in daytime, if its a quiet road and/or a public holiday that will make that intersection virtually unused. Stopsign = flashing red light for all sides, of course.
As I said, speed humps - bumps are mostly obsolete - are not necessarily a good solution. Redesigning roads works much better. But those also cost a lot more money. Money almost always wins.
I love the Idaho stop law! I use it very often and it allows both cars and bicycles to get through intersections faster. My commute to work includes several stop signs including three 4-way stop signs. If I am approaching a stop and there is a car coming but I can just continue through before they have a chance to stop, there isn’t that awkward “you go”, “no, you go” dance that happens so often.
I’m also perturbed when in WA (I live on the border) and riding and hit a stop light with sensors and you are the only one around. Run it and you are breaking the law. I’m supposed to act like a car but I would never take my car onto the sidewalk so I can press the crosswalk button. This scenario is also true when I ride one of my motorcycles. Many lights aren’t triggered by bike or moto. I have complained to my city about one in particular that never triggers by moto. When I used to commute to work by moto, I would always have to run it (I go to work very early). Does the Idaho stop law apply to motos? 
I thought I would check in and report on recent events near me.
Two days ago, one of the lesser-used intersections near me changed to blinking red for one street and blinking yellow for the other street. Let me just say…
I LOVE IT! No more waiting behind red lights for non-existent cars on the other street.
I assume that the light logic circuit fried or errored and this is the fallback default mode. I also assume that the traffic light guy will come along eventually and “fix” it, to the chagrin of us ignorant masses that are happy at the free flowing traffic.
But until then, we will enjoy it.
In older areas of cities there’s still lots of traffic lights at intersections that really don’t warrant them anymore because of depopulation, traffic diversion to newer interstate highways, or any number of other reasons. At the time it was installed, the light was almost certainly warranted, whether to allow gaps for side street traffic or for turning traffic. They wouldn’t have been put in “just because” since they’re actually quite expensive to install, operate, and maintain. Today a simple 4-way intersection without turn signals can cost over $100,000 with all the pylons, footings, underground conduit, sensors, signal heads, wiring, and controller cabinets. Anyway, it doesn’t mean they couldn’t be removed now due to changing traffic patterns, although sometimes they’re necessary simply because of visibility.
The one big problem with flashing lights is that you have to also be able to see the signals facing cross traffic. If it’s flashing red in all directions, no problem. I think that is or should be the default failure mode. If one way has flashing yellow and the other flashing red, that’s when you get into a dangerous situation. If the side street that sees flashing red can’t tell that the main street has flashing yellow, and assumes they have flashing red too, then they could think they have the right-of-way and boom. That’s why signals tend to only go into flashing mode well after dark and stop before sunrise, so you can more easily see those perpendicular signals. I don’t think that’s part of the traffic code, and there’s usually no signage to indicate who has the right-of-way during flashing, so it’s a safety and liability issue.
As others have said, they do exist. They are not as awesome as I had hoped, however. There are some on my way to work and I’ve sadly learned that although they do let straight traffic continue if there are no cars on side streets, one car on a side street being detected means stopping for the entire cycle - it can’t stop traffic for that one car and go back to green.