For background I'm a retired volunteer Fire Chief.  This is something I've discussed, talked about, preached about, and complained bitterly about.  I've felt like taking a crowbar to a helmet a couple times.  And as great as we get along with cops in this area, some of the state cops are the worst.

Dim your headlights on scene.  Or if not needed for lighting turn the headlights off.  I can't count the number of times I've been on scene and couldn't see anything for the blinding bright headlights of a firetruck, ambulance, police car, or volunteer responding directly to the scene

As for the light bars, yes, there needs to be a daylight and night setting.  Also discussed several times.

Keep in mind volunteer departments and small town law enforcement usually work from a very limited budget.  The comment about $500,000 firetrucks is true.  But we won't get one of those until it's been replaced after 10+ years.