Well, there is a really good reason for that, one that was actually pointed out by one of the nations leading SWAT Team Training Units Bob O'Brien, who writes at Police One Magazine.
He pointed to the FBI statistics of violent crimes reported and investigated, the number of emergency SWAT callouts, verses the actual number of SWAT reported raids and the reason for such raids.
He showed where nationwide round 3% of the total yearly SWAT operations were for actual violent crimes such as active shooters, hostage situation and other such crimes where one can clearly see the need for such a group.
The most common use for SWAT Teams were for search warrants and drug raids where first time offenders were targeted and the most common results was either nothing being found in the search or misdemeanor amounts of dope.
And as Radley Balko points out SWAT TEams are 15 times more likely to kill someone during a raid than to have a member of the team even assaulted much less killed.
why would you even use a swat team for this? ridiculous over militarization of the police force.