Cops are all unionized? Really, I’d like to see the numbers on that.
Cause in not one of the four departments I worked for were we union.

All federalized? Youre kidding right?
Little secret, most cops can’t stand the feds.
Secondly, our “contract” is with the city, county or state depending on which agency. The feds have zero control over local LE, they can request assistance but it does not have to be given.
And if you think local LE is just going to sit back and be put under some federal umbrella, you obviously don’t know many cops.

That “posse” is because of a mutual assistance agreement, that way not one dept has to foot the bill, and it gives a wider diversity of knowledge, the local officer can put forth info that someone from elsewhere can’t. It also gives a wider jurisdictional authority to the officers involved, any one of them can make an arrest while a part of the task force, not just the one in his own area.

You may want to do a little more research. Call down to your local PD and do a ride-along or two, get some real answers from real cops. You may be surprised.