or one title/city is holding the entire database to be corrected if something gone wrong ?

The 40k came from selling out their database.

@Lance JohnsonYou could reverse engineer the county assessor site API (through inspecting network traffic), then iterate through all possible parcel numbers, storing the results and their data in a database.

It's a little disturbing that anyone can type your name into the county's real estate database and pull up every property you're associated with.

As an example I have been in the business for almost 15 years so the sites you mentioned I have a database of thousands of sites I have built up over the years with my network.Even within the larger NNN listing brokerages lot's of their properties never go to the main company website.

In fact, it creates a lot more expense and time for just that reason.I have used several different database tools. 

Creating lists that no one else has.I've been helping professionals monitoring probate and pre-foreclosure leads in real time streaming the leads to their CRM to pulling parcel data directly from county appraiser database at scale.At some point you will realize that these "national coverage" companies just won't have the fine-grained information you need to help you succeed in your counties.

If you build a database of other investors you will find parks.

If you have incoming leads or a database of expired listings, preforclosure, etc. you register a new phone number with your EIN (we help with this) and then plug your social media, email, into the AI.

If they don't have an working email linked in the realtor.ca database it likely won't work.