Should probably clarify in the title that this is for property management, not real estate. MLS data is notoriously impossible to get without huge contracts, which is what made want to check this out.
It's just extremely valuable, so they won't give it out willy nilly. There's a network effect at work, where it's almost impossible to sell your home without listing with them, so everyone does. And mortgages are just about the most lucrative consumer financial transaction there is, so lots of incentive to keep it on lock.
""" Can buyers access the multiple listing service without a realtor?
The short answer is no, they can’t — at least not directly. In order to access the MLS, you need a real estate license, which means it’s not possible for buyers to have direct access to this data on their own. However, they can reap the benefits the MLS has to offer if they start the house buying process off right and partner with a local real estate agent. """ https://listwithclever.com/real-estate-blog/get-access-mls-w....
Credentials: Sr Product Manager at Amazon in the RE Team (Amazon Fulfillment), former BTS commercial property developer, and current luxury residential Real Estate agent with MLS access.
Most of that data is sparsely updated and I'm not clued in on many real estate APIs to track up-to-date trends in housing and prices so I would love to know more about what your work looks like!