Whereas something that is well known and homegrown in the USA (Timothy McVeigh, anyone?) has had a much lower level of concern assigned to it until very recently.
I think two "issues" are the relatively better protection against surveillance US citizens have (I wouldn't think it's an issue at all, hence the quotes) and the fact that they tend to be lone wolves more than Islamic terrorism, which often works through networks.
So it's not that easy to spot people like McVeigh, Kaczynski, or outside the US Breivik, before they act.
- victim becomes a martyr despite being "no angel" (Weaver was a white supremacist, dealing in illegal firearms)
- initial involvement of law enforcement is entrapment (undercover ATF agents)
- lies by law enforcement ("the ATF filed the gun charges in June 1990. It claimed that Weaver was a bank robber with criminal convictions.[27] (Those claims were false: at that time Weaver had no criminal record. The 1995 Senate investigation found: "Weaver was not a suspect in any bank robberies.")
- basic cockups (court date mixup)
- absurdly long quasi-siege
- significantly lighter treatment and more investigation than similar fiascoes for nonwhite people (e.g. Breonna Taylor); the 2020 version of this would probably have just been to drive a MRAP through the shack and use the return fire as sufficient justification for the killings (see e.g. https://www.forbes.com/sites/erikkain/2011/08/31/actor-steve... )
- they shot the dog. They always shoot the dog
- attempt to prosecute sniper is met with sovereign immunity, case is dropped