As a retired realtor, the TRUTH is realtors own the MLS system and intentionally limit the information sent to websites like Zillow, Trulia, etc. The reason is realtors need buyers like you to call them for the missing information so they can hopefully convert you to a client. If websites like Zillow and Trulia had all the search filters that the MLS systems do, then buyers like you would have no need to call a realtor. This would slow down their business or put them out of business and no realtor wants that.
Items deliberately left off of real estate websites:
property taxes in states / counties that do not disclose property taxes - Texas does NOT disclose property taxes.
filters to search for specific types of homes - ranch, 2 family, townhouse, co-ops
rentals - whether pets are allowed or not
if home is located in school district that the website says it is
You can type "ranch home" in the Keyword search box but the results will not be specific to just ranch homes. Bottom line - a realtor can email you listings directly from the MLS with your specific criteria. No charge to you.