And almost all of these brokers are representing big name companies like SRS, Marcus & Millichap, Horvarth... etc. 

I check the SEC, FINRA, ratings websites for inside information on the principals in the company.

I think the reality is that Airbnb is a larger company with a larger IT department so their software is more sophisticated and they have the staff to make software changes in a timely fashion to meet state and local laws.

Caveat here is that it is possible if you put down a large down payment.Some angles to consider here are properties with lots of bedrooms which you could rent out by the room, or larger lots that you could improve (ADU) and force appreciation on.

I am wondering if it is possible to set up a legal self insurance company for rental property insurance?

Urban STRs were hit harder due to the heavier restrictions in larger cities.Regarding the rural vs urban, I believe in beaches, lakes and mountains for any STRs I look at.

You can find a company that doesn't have a high spend/volume requirement and flexible pricing options based on your needs.

Larger capex investments like new roof or windows can be scheduled based on your cash flow position but need to be addressed rather than just pushed off.

However you are missing out on strategy that will likely save you more in the long run, IF your goal is to grow into larger properties or take advantage of cost segregations 

DC it is a much larger concern.