Anyone can be the 'tap taker'. The point being there is no point tapping it then passing to the kicker to attempt a 20/40, when you can kick it straight from the 20 and get the scrum feed wherever it goes out.
Good point.
Really the only use for this is if you've had 4 tackles in your end and still somehow haven't crossed the 20, and you're totally desperate.
If you've got more than 1 tackle in hand, you would obviously try to gain another 15-20m and go for the 40-20
It's an extremely high risk play with a mediocre reward.
3 outcomes -
1 - you kick it a lot shorter than you would have just going long and straight, losing valuable position
2 - you kick it out on the full, giving the opposition a very good scoring chance
3 - you succeed, and get an attacking set 40m out, so not even that close.
And why would wingers bother dropping for such a low % play? Even if they nail it, still got 40m to defend the reset.