The difference is, there may well be a number of cars that are superior in a race situation than the META. Your example, while for effect, was not valid, because the 500 would not be better than the Mercedes AMG F1 car in any circumstance!
And there are many things about the racing in GTS that are, by design, not 'simulated' in order to achieve the best competitive environment. I think grid position based on your best time in any car provides better drivers with the potential to start ahead of lessor drivers.
If you are whining about that, just grab the META and put in the faster lap so that you start ahead of them! And if you choose a different car to race, it should be because it's better than that one, so you get the best of both worlds!
Otherwise, I would say the fix is improved BoP, which they are constantly re-evaluating, so I don't know what more to ask.
For Daily Races, the short nature of them and 1-and-done consequences mean I would rather they consider my abilities overall, not just how good I am in a specific car. I want to be able to start ahead of guys that I am better than, each race, not be limited by the car.
If you're worried about guys who use the META, then switch to other cars and can't handle themselves in the front, that's the point I made above: just qualify in the META yourself, and voila, whatever car you choose, and whatever car the lessor driver chooses... you are starting in front, and have the advantage you deserve. Competition issue sorted.