Some of the information given does seem intrusive, like assessed taxation values for your neighbor’s house. The same goes for house square footage. On the other hand, this has always been public record; it’s just that it didn’t use to be so readily available.
At least, it doesn’t give the names of owners and occupants.
But other information is provided which should be far less troubling as to privacy concerns, and far more interesting to the innocently curious person who wonders when something was built. Many of us drive or walk by a house or building that seems out of place in its neighborhood and is clearly much older than its neighbors, and want to know more about it. Or the same thing happens when we discover a tiny one-block street of old houses otherwise surrounded by commercial and industrial properties.
In Los Angeles, these questions can sometimes be answered by the Property Assessor’s Information System (PAIS). For instance, here’s the listing for the Capitol Milling property on the northern edge of Downtown, listing early “improvements” to the property in 1889 and 1894. (Enter the AIN 5414-014-001 where it says to.) From what I can make out, the earliest listed improvement isn’t necessarily the original build date; in the case of Capitol Milling the building is known to have existed before then, even if what stood originally has been concealed by extensions put in later. Also the PAIS appears to omit completely any information on school properties, as it does the Plaza neighborhood which has been state-owned since 1953. Still it’s useful and often interesting for odd places here and there around town, especially the sorts of small commercial structures which have never decayed and then been noticed and refurbished by preservationists, but rather have simply gone on being used as stores or small office buildings, and, as a result, gone on more or less unnoticed.
I imagine other large counties around the country have the same sort of system in place, so fellow urban archaeologists, have at it.