You don't grasp the situation. A single good bowler will rarely take 7 wickets by himself in every innings to get to the tail enders to get cheap wickets. The most number of wickets per innings by a bowler is around 4, which means you need other 3 to come from somewhere to get to the tail to get your cheap wickets. But in a good attack , almost always you get to the tail, and hence gets opportunity albeit shared to go at tailenders. It's not the case in a lone ranger who gets 6-7 wickets in an innings once in every 10 - 15 bowling innings. For even to have a chance, somebody must take 7 wickets!
No one talked about cheap wickets. We're talking about wickets in general. The players we're talking about are more than capable of taking any of the batsmen around the world and don't really have to rely on cheap wickets. Therefore the 2% advantage is exaggerated, if not irrelevant.
Furthermore, the player in the group will have teammates taking 2-3 - if not more - wickets regularly, each, in each inning. That means for him to even have a large wicket haul means he has to work harder to take a higher proportion of wickets. If he doesn't have the competition, he is much more likely to take those wickets.
What you've shown is that Aus was 2% more likely to get to the tail than SL, yet their bowlers still had more competition for those 2%.
But he has to bowl his team mates share to pick it up, against the fatigue. Such players are in a disadvantagous situation.
So? He bowls more and takes more wickets. That's a given, that is the point of the discussion. It disadvantages him in terms of it being harder to stay fit bowling more career-wise, but it doesn't really hurt his chance at better figures - because we're only talking about a handful of overs more per match or when the situation arises, to get the ball more.
Also, this is probably more of a problem between pace bowlers. Hadlee for example only bowled 3 overs more than McGrath per match, but has many more bigger hauls - in about 40 less tests - through the lack of competition, which shows that it's not entirely just about bowling more; and having less competition for wickets helps a lot.
No it's not. You are simply forgetting that he has to bowl more for it and has to race against the fatigue.
Again, depends on the bowler. Do you think it's really going to kill a spin bowler to bowl 5 more overs per match? Highly unlikely. It'll be felt more towards the end of his career than during matches.