A friend of mine which is an RCMP officer told me the same thing to do years ago. A locked car won't deter them if they really wanted to get in. It would save you the insurance deductible plus a lot of hassle in the long run
Locks only keep good people out.
I don't buy into that theory one bit.
I have personally seen thieves at the store parking lot walking around checking door handles. If it's locked he would move on. He never got to any unlocked doors before I back checked him into the car he was trying out.
Yes, checking door handles is one method. When there is a high probability of people hearing a car window break or they have release conditions not to possess tools, they check the door handles. Even if police caught them...
1) Witnesses usually cannot pick out the thief in a photo lineup. The distance between the thief and the witness is too far away or too much time has passed since the witness saw the thief.
2) Checking door handles is not a chargeable offence.
Trust me, thieves are a lot smarter than what people give them credit for and they skilled in their craft.