Why would you go through all the trouble to write long-ass manifestos calling out certain ethnic groups or government groups and then go shoot some complete rando civilians? Why would you drive by government buildings while on the way to a public place for your shooting without stopping there? It makes no logical sense.
The only non-MKULTRA-style explanations I have:
For 1), that's just dumb. If you're going to write the manifesto and throw your life away, it hardly matters if there is security. Plus you can pretty easily sneak up and surprise some cops or something from behind for at least a couple of shots. People just can't be on guard 100% of the time.
The second is my preferred explanation. I think the media-state complex enjoys getting the public divided and eager to hand over yet more power to the state, so shootings in the public serve a useful purpose and are not actually a problem to be solved. On the contrary, they also serve as a safety valve to direct the unstable wackos out there against commoners that they don't care about rather than risk challenges to their power. The media gets more clicks, the politicians have threats to their stability removed and get more power, and the public gets killed. Win-win all around. It's pretty fucking sick, really.
I'm not sure what to do about it other than spread this idea around so that these troubled individuals find more productive outlets for their frustration rather than killing random members of the public. It could be a good mechanism to encourage good behavior and accountability in politicians and business people.
I guess for 2), it's probably a lot more difficult to find a location with several rather unprotected powerful figures, so the shooter might only be able to bag a few and not get the blaze of glory they end up with from the public
It's true, no politicians have ever been shot in the US