Why don't DMV or places with incredibly long lines have SMS notification?

Everybody in California knows about the lines at a DMV (Department of Motor Vehicles). If you line up at 7:30AM (it actually opens at 8), you may be out by 9AM. If you like up at 9:30 AM, you probably out by 12PM. If you line up any later, you may be out before closing, but just barely.

They have an automated system now that gives out numbers, and then automatically announce "F07 at Windows 14" but it's still dumb. You never know how fast the line moves, so there's no estimate, so you're pretty much forced to stick around FOREVER, and if you happen to miss your slot...

Pharmacies like Walgreen can send SMS to your number to let you know when your perscription is ready to pick up. Why can't DMV do something similar? Say you're F47, you'll get a SMS when the queue is like F42. Then you can reply with CANCEL if you want to abandon the place (like you won't make it back).  The system can even predict how fast the wait will be based on the last 10 people processed.

How much would such a system cost? Minimal, and actually fit within their existing system. Should cost less than $1000 per DMV branch, plus cost to send the SMS, even less if you don't want the "CANCEL feature.