its the easy way to steal the scratch without a human witness. However if you suspect this shit is going on, there is federal regulation about light timing:
this is the federal specification for yellow change light timing:
16. Q: The MUTCD specifies that the duration of the yellow change interval should be between 3 and 6 seconds. How is the actual length determined for a given intersection?
A: Within this 3 to 6 second range recommended by Section 4D.10 of the MUTCD, jurisdictions are free to set yellow change interval timing based on their own policies or studies. ITE has published guidelines for determining the length of yellow and all-red intervals. (Visit ITE's website at www.ite.org where you will find additional information under "Technical Information".) Those ITE guidelines utilize scientifically derived formulas based on engineering principles and years of research. The yellow change interval is calculated based on speed of approaching vehicles, the stopping ability of approaching vehicles, and the width of the intersection. The ITE guidelines are used by many jurisdictions as the basis of either the overall policies or the individual intersection timings for yellow change intervals. Because vehicle laws vary by State and conditions vary by intersection, the engineer must exercise judgment in deciding on the length of the yellow interval.