There is a LOT of work that is required to make these online plans ready for permit.

If permitted, I'd imagine I would need to work with USPS to create a "dummy" apartment number that would be recognized as my business mailing address for the property. 

Was able to find a Home Depot approved contractor, and get the whole thing done for $1400 including permits. 

Plus whatever the local jurisdictions cost for utilties, public benefits, permits, etc.

The law permits any person to assume possession of an "abandoned" property. 

After living here for about 1 year, we built a tiny house in the back yard (all to code and permitted).

You can ask around to see what your county requires to get the proper permits for a construction project like that, but oftentimes they require an architect's draft of the additions and multi-stage reviews by the county of the additions in the various stages of being built, among many other things.

I recently consulted on the construction of 250k sqft of office/retail that has been fully permitted for 7 months now with no outlook of being built due to leasing difficulty.

The point of all this is that the lower these costs are, the more valuable the lot is to a Builder.Also it is worth more if the building department is easy to work with and the building permit fees are low. 

The standard TREC contract states "Seller shall permit Buyer and Buyer’s agents access to the Property at reasonable times."