Yes they don't, mostly because it's a relatively small group of individuals dispersed in a huge country. The same cannot be said of the Iranian government.
Wiping out the Iranian government will only strenghten the IRGC and other rabid anti US Iranian groups politically. As demonstrated by the recent US strikes that killed Ali Khamenei, wiped out senior Iranian leadership and that girs' school.
This would be incredibly stupid. An attack on American soil could be met with a literally nuclear response against Iran or whoever perpetrated it.