Depending on the type and performance of aircraft, insurance companies do give reduced premiums for aircraft if hirers are checked out first.
Please don't confuse service with price, the check flight is a very small charge compared to the long term hiring costs. Some establishments give you more service/advice (free help) for the price and then some just charge a lot for a clapped out old Warrior.
I have done a lot of check flights in my time and I've found generally the pilots that don't want to do a check are the ones that really need them, irrespective of hours or flying back-ground.
I wish i didn't have to do them when I go on holidays but hey they don't know me from a bar of soap so I don't mind.