Random, spontaneous acts of politically motivated violence are heavily ignored by news media, academics, and policymakers. Ignoring these cases is especially problematic given that the spontaneity of these incidents increases fear among a targeted population. However, the broader implications of the resulting fear in minority populations never plays a role during the prosecution and criminal adjudication of the perpetrator. We theorize this is because the perpetrator is viewed as a traditional criminal, or at most, a hate crime offender. As such, these cases wined through the courtroom without the significant attention given to others who become classified as terrorists.
This lack of attention severely limits how the United States perceives far-right domestic terrorism. Largely, these attacks remain a localized issue, appearing only in a single 24-hour news cycle. This is particularly true when law enforcement never identifies a perpetrator. Only when the United States gives far-right ideologically motivated attacks, particularly spontaneous attacks, significant attention and identifies it as terrorism, can we fully grasp the extent to which the American far right poses a threat.
https://www.radicalrightanalysis.com/2019/04/03/far-right-terrorism-the-problematic-case-of-spontaneous-attacks-a-quantitative-study/

Then how do they know it's right wing?
Trust me, when somebody sets a fire in a Brooklyn Synagogue, 90% chance it's Blacks or Muslims (or both), 9% a fake hate crime by an edgelord Jewish kid, not Wilbur Jones from the Tennessee Trailer Park.