I would say that no, that shouldn't be. TT and SR share something in common with each other that the Scar doesn't. That's laning, or farming phase of the game. It's important to avoid giving passive exp gain, due to it countering the denial strategy, which is a critical component to the early advantage you are talking about.
Yes, Garen is going to try and deny you because he can dish out harder, and heal better than you. All you have to do is not push the lane. If he is denying you, go gank bot, farm the jungle if you can, or recall. If all else fails, go into the Dragon's den so you can at least keep up in levels. Learning how to accumulate your gold/exp in other ways aside from just farming is important to learn, as it will allow you to adapt to the way someone else is playing. And that is one of the more important things for people to know.