I personally wish SWAT wasn't needed for every dangerous call, normally patrol units can eventually sort it out. So I personally think instead for some of the SWAT missions, its a request probability thing. Like: "6 SWAT Personnel Request Probability: 10"
But, I wouldnt have an issue with this if SWAT SUVs functioned as patrol cars. When I was setting up my patrol routes it the SWAT SUV showed up, so it look like it supposed to or it could be.