Isn’t most of the insurance for liability? I can see a logic where older cars are less safe, and thus accidents are more likely and would cost more, hence the higher costs. But I’m just guessing.

I don’t think I’m a very good DM, but all of my players ask me for DM tips when they’re doing another game or one-shotting or whatever, so maybe?

I love this! And if you find yourself afraid to even entertain an idea, perhaps you’re afraid that you’ll find it convincing and accept it. We should WANT to be convinced, because that means the different idea holds more merit than our current belief!