I have seen more than 1000 street races and not one even near accident nor marginally dangerous situation.
Dont race in populated areas or where you cannot see 1/2 mile at least.
Non issue.
I'm sure I've seen at least as many street races and was involved in at least 500 myself when I grew up in the 80's. We always tried to be safe. The rule was if you were racing and someone appeared on the highway you immediately shut your car down and got in the rt. lane. But there always had to be one (or 2) idiots in the bunch. Saw one real close accident. Why? Cause 2 16 year old kids (with both cars full of kids) just had to prove that they had the fastest cars. They ran 2 cars completely off the road down into a big ditch that were coming at them cause neither would shut down until the 1/4 was over. :wack:
Things may be different in Sweeden, don't know. Looks like they were just running short runs so that helps. Looked like well organized fun so it may have been fairly safe.