Weather stations for home use can be very accurate. However, the reliability factor involves whether the homeowner will recognize his weather station is not working properly and will fix it promptly.
A rachio user relying on a neighbor's weather station would have to have to spend some time verifying it was continuing to work correctly, because the neighbor's motivate to fix problems promptly cannot be known. Some people put up a weather station just to satisfy their curiosity and not necessary to interface with an irrigation system that depends upon accurate information.
Rachio only checks the weather once per day, and the time between checking and watering your landscape may be several hours depending upon what type of schedule you have set up.
One thing you can depend upon is that a commercial station is more likely to be monitored for continued normal operation and promptly repaired should an anomaly be noted. This is one less thing a Rachio user has to worry about.
An even more accurate watering schedule could be envisioned based on expected chance of rain, rather than rainfall already recorded. Would you want to water today if weather report was for showers tonight? This is where user intervention can save a few gallons and be even smarter than the computer.
While it is always possible that it could rain AFTER Rachio checked the weather but before the irrigation cycle started, this has to be a relatively rare event, even in Texas. Also, Texas is not known for requiring extreme water conservation becuase of the frequency of rainstorms.