Read actuall speed limit signs with the cameras

This feature is common in most vehicles today; At least in our region the speed limits from the navigation data is more then unreliable and even dangerous if the speed limit is set to "unlimited" even when there actually IS a speed limit and the car is rushing forward with Autopilot or TACC activated.

On the opposite side of this argument, what if the car reads a 45 and then heads into a 25 school zone where the speed limit sign is obscured? 

Nevertheless, I do agree the car should read speed limit signs allowing tesla to somehow use its fleet to rectify bad speed limit data. 

Apparently, There is a company (Mobileye Vision Technologies) that Patented the process of using cameras on a car to read speed limit signs. Telsa used that companie's cameras/software in hardware version 1. So those vehicles are capable of reading speed limit signs. Since Tesla has taken everything in house, they've had to stop using that functionality.  I'm sure Elon/Engineering team are working to see if they can come up with a way to get around that patent or use it at a reasonable cost, but for now it's not the ability to read signs that's stoping them. Its complying to patent law.

I hired a low-end Toyota Corolla and it had this feature.  It was so uncannily accurate, it picked up school signs, roadwork signs, in fact any sign that looked remotely like a speed sign.