As soon as I saw the image this is exactly what I started doing in my head.

I finished this in 8 moves? Not that hard

No they don't. They still have nightmare of item contamination.

Tbf, they also have the arthropod invasion sorted out.

I did, then spaceage broke all my old intersection templates

They were stuck for 10 minutes and needed to be directed from the outside. It's maybe not that long, but they struggled with figuring it out. Source (in Norwegian, this happened in Oslo): https://www.vg.no/...

there are probably cars there facing the bottom bus, no? it's the enter lane, not an exit lane

It is, but none of the four bus drivers have all of the information. You will also need two or three cops or at least guys in fluorescent vests to physically block traffic from entering the circle and or bitch-slap selfish asshats as necessary until the Gordian knot of buses is untied, otherwise said selfish asshats will try to barge into the intersection the second the first bus moves and start everything all over again.

Also, fewer cars will help.

I think it was a combined, synchronized effort

Bus on left hand side of screen sealed the deal, but it was a concerted effort of fuckery

Each one of them screwed up independently. It takes a concerted effort to reach this situation.

I don’t know what’s going on in this picture, but, whatever it is, being accidental is last on my list of possible explanations

In my opinion the stupid bus that entered the round about when already 3 buses where in there.

I mean get that there was space, but man you could have waited 20 seconds and everything would have been fine.

It's a deadlock situation and can arise without any screw ups. Imagine the buses being 5x as long and all reach the intersection at the same time as an example. All have space to enter the roundabout but they'll reach the same situation as in the picture.

To fix this people uses signals and can be done by having the buses follow "Only 1 or 2 articulated (double) buses are allowed into the roundabout at a time". A rule like that might be required if you have a lot of articulated buses. The risk of this happening depends on how many ways you can enter a roundabout no a bus like that, how long the buses are, how frequently they run and how big the roundabout is.

1 of 2. Either the car drivers going on the inside of the busses, hindering them enough space to make the turns, or the bus drivers allowing it to happen.

Kinda looks like a cop to me

Honestly I've never heard about a roundabout traffic jam before seeing the picture of the Norwegian four-way bus lock a couple of days ago, followed by this example right here.

I think Cities Skylines is either badly programmed or propaganda for Big Intersection.

Buses stuck

Step bus, what are you doing!??

happened again

If all four arrived and entered at the exact same time, the exit might have been clear for all four.

Why though? If you zoom in you can see that they're literally filled with people and allow easier/quicker stops as they have many doors. If you actually plan their routes they work quite well.