There is, but the effect isn't as good; you'll still get channel congestion from non-prioritized control traffic, and hidden-terminal issues where devices don't

There is, but the effect isn't as good; you'll still get channel congestion from non-prioritized control traffic, and hidden-terminal issues where devices don't know there's a public-safety communication on the band. Plus this makes it less likely for accidentally or deliberately non-compliant devices to jam communications.