It is a feature of all motor vehicle policies now but I am not convinced they really know what they are talking about. For example, I recently renewed my car insurance which included 30,000 business miles and 5,000 private - the premium was £356 fully comp. I left the job I had so contacted the insurance company and told them 10,000 private only………….£347!
I have also been told by my bike insurer that I would not be covered if I exceed my stated annual mileage although they have not asked for the current figure - previous companies have. This is a similar situation with using it for commuting and if you are unemployed.
Ultimately they will tell you that the policy premium is based, among other things, the level of risk relative to the mileage.
Just another way to upsell I am afraid.