Why would you lie? Pretty easy for them to find out your life schedule.
They have discounts for yearly mileage driven as well as the "less than 15km to and from work." If you have the below 15km coverage, you are allowed to drive the vehicle to work, up to 6 times per month. I know of a lot of people that get this coverage, and drive over 15km to work, 5 days a week. Pretty risky to save a few bucks.
People making false declarations on insurance to save a buck? Yes it happens and happens a lot.
I just have a hard time with insurance companies trying to put people in a box to find reasons not to pay. Life isn’t binary black or white, what if I stopped at work on the way to Costco that day? The concept of unlimited mileage for pleasure but limited distance to work is a very odd concept to me.
That being said, if people are knowingly picking a plan that clearly says you are only allowed a very specific distance a few time per month, then that is different.