Also, "Premium Ammo" is by design absurdly expensive to the point that it's very rarely used except in clan battles. We're talking 10 cents per shot at the top tier. Also premium ammo only changes penetration, not damage. It CAN affect the outcome. Yeah I've had my Tiger 2 penetrated by a KV with gold ammo - ONCE in over 2,000 battles. I'm not butthurt over it.
Premium tanks aren't actually better than their counter parts - the Hotchkiss is the only exception being a Tier 2 tank with Tier 3 armor. People whine about the Lowe, but as a Tier 8 tank it's not as good as the Tiger 2 or the IS-3, admittedly it's better than the T32 but only because of the change to gun depression on the T32. So in short, Lowe is the 2nd worst Tier 8 tank due to being slow and poorly armored in comparison to other Tier 8s.
Why do people drive Premium Tanks? Because Premium Tanks have a bonus to income. So my Tiger 2 makes 50k while a Lowe in the same battle walks home with 70k and lower repair costs.
WoT does a fantastic job keeping the game free to play and yet balanced. Yes you can pay for faster advancement, but it only affects you. Yes you can pay for a bigger tank, but that just means you get in games with bigger tanks - not that you'll drive around in your pwnmobile oneshotting helpless newbies.