You're not comparing like with like, folks. Yes, when an insured driver hits you, you have the option of claiming off his insurance. However, if you do that, you take on a load of work on yourself. You might have to argue about liability, in a disputed claim. You need to deal with the expert claim assessors at his insurance company. You are probably not an expert in assessing damage. You don't know the industry standards for allowing rental for a replacement car. You mightn't be sure of your rights if you choose not to actually carry out the repair. It's not impossible, but it's hard work.
Part of the reason of paying for comprehensive insurance is that you get paid for damage to your car, regardless of who is at fault. And you don't need to be a hardass negotiator. You pay a price, in terms of losing your no claims bonus.
But apparently, if you get hit by an uninsured driver, you have the luxury of getting it sorted by your own insurance company, without worrying about your NCB.