I will just say this. It is easier to hit a golf ball straight then to return a 130 mph tennis serve. Does that mean tennis is harder than golf, not necessarily but with the right practice most people can learn to hit a ball relatively straight. However, you could train all your life and you won't be able to return Andy Roddick's serve. It's all a horse a piece.
Not exactly a fair comparison. 130 mph is pro level serving.
So saying "hitting a ball straight" isn't a fair comparison. Try "hitting a ball straight over 300 yards". That's more relative.