Every officer takes an AR

Ah you think rifles are assault rifles. That explains a lot.

I work in the same building with them. Every officer takes an AR and body armor to the squad car when heading out to man their speed trap and bring it back at the end of the shift to store in their air-conditioned locker (not just the locker room - the actual interior of each locker itself has its own thermostat and air supply).

Sounds like 90% of your complaints have nothing to do with militarization, however valid they are.

All that being said, there is a need for specialized units. But the big change the US has seen over the past 25 years or so has been giving SWAT-style weaponry and resources to everyone. The traffic cops pullings people over for speeding in a school zone don’t all need riot gear and an AR in the trunk.

Even citing your own unverifiable anecdote you failed to explain how your traffic cops have riot gear, so I don't know why you're re-asserting it as fact.

Detectives performing investigations don’t need access to tear gas and flashbangs. But for major cities with thousands of occifers, having a few dozen specialists makes sense.

I'm sure they figure they want to be self-reliant and not have to depend on another agency. Is your county agency objectively the same quality or better? If so, as long as the plurality of voting residents of your city don't mind the much higher response times in emergencies, your point here makes sense. Otherwise, it does not.

Small towns used to just call the state or nearby major city for assistance if they needed heavier equipment or tactical units. Now they all have the heavy equipment

Again, mostly because American voters have insisted the equipment and training is distributed down the pyramid in the wake of things like Columbine. There's pros and cons, as described above.

The police had just gotten a new-to-them MRAP, and instead of talking to the kid or just using the key the parents had given them, they drove a tank through the front of the house

Are you conflating MRAPs with tanks?

I understand this and the Rifle vs. Assault Rifle issue can seem pedantic, but if you actually want to address concerns in an objective, solutions-focused manner, you should want to be accurate.

Obviously if you're just venting it doesn't matter, but I like to solve problems rather than (listen to a) vent about them, so you can just save yourself the effort.