Until you're 25, car insurance is prohibitively expensive, and yet at the same time completely necessary. When you're a young adult, the one thing you don't have much of is money, and so any way you can get or save money, any money, is a huge draw. 20% of £2000 is £400, a significant sum.
Being tracked is of secondary importance compared to saving some money.
When you're older, car insurance is not so expensive anymore. Plus, there's a good chance you will be earning more money too. At this point, saving 20% of your insurance might net you £60, not inconsiderable, but not going to change your year.
I'd prefer a simpler system for younger drivers. It seems unfair that many of them are penalized, or potentially spied on, simply because a minority of this class of driver cost insurance companies the most. Insurance should cost more for them, but it should be rebated or rolled-over each year to the same as an over-25 if they have no claims.
Eg, £2k for fully comp for a year for a 19 yr old, same car/town might be £400 for a 30 yr old. After a year of no claims, the 19 yr old's renewal is only £400, or £2k if they made a claim. This may be unmanageable, doing the sums may make the 19 yr old's 1st year costs too high, since subsequent ones are not as high..