Having worked in insurance before, I've had numerous officers stop in to our office to validate insurance cards because they've been doctored.
How that works: person A signs up for a policy, pays the minimum pymt. Gets ID cards, stops paying after first payment. Policy is canceled but ID cards show valid date for 6-12 months. Person A then edits the document with new dates to show future proof of insurance without spending money. Might trick some initially unless you get into an accident.
However, not everyone is so skillful at matching fonts or size, so often it'll look like shit and be obvious its fake. Maybe the officer thought some database was surely more accurate, but should've done a little research first before issuing a ticket.