I gave one example, and I'll give another. I'm virtually positive that the Norman Oklahoma suicide bombing outside the stadium was an instance of failed terrorism. But the perp is dead, and his friends are unlikely to put themselves on the jail list by speaking out.
Of course, you can argue that it wasn't terrorism, but I find that simply incredible. It's just that the authorities and the terrorists, probably a local group, share a mutual interest in keeping it quiet.
Same with OKC. There was Muslim involvement in that, several obvious connections, but the FBI and the terrorists have agreed to cover it up.
Terrorism without the terror. Interesting. And, your examples are horrible.