Community Update

I've heard that some police departments are using license plate scanners to track vehicles. Question: What crimes will tracking prevent?  As an extreme example,  the Russians told the US about the Boston bombers,  but nothing was done to track and stop those people.  I've got the feeling that plate scanners are just technological toys for government to claim that they are protecting American citizens from crime.
I also feel the $$ spent on this equipment could be better used elsewhere.