Er, because that is what the rules say?

the player isnt in control of what the crowd do, nor the ball boys. Whats to stop the home team putting loads of ball boys behind the goal line and telling them to get to the ball ASAP to stop the away team ever getting a quick tap.

The obvious rule should be to just have balls available around the ground with players able to pick one up and get the quick tap.

I disagree. The match ball is the match ball. I know that they now have several available, and I have no problem with that at all, but the same rules have to apply to both teams for fairness. If it was allowed for the home team to set up ball retrievers for the purpose of devising quick taps then that is unfair. If another ball comes to hand quicker than the player who ultimately takes the tap could have got it himself, then again I have no problem to it being used but not if the defending team is disadvantaged, as the time saved is artificial, it would not have happened had the match ball in play been used.

The reason it is unequal is simply because (obviously) the home ballboys would never do the same for the away side. And the away side are not allowed to bring a host of ballboys themselves. Although the idea of competing squads of ballboys trying to effect or prevent quick taps does have an amusing air of farce about it!

its a possibility though.

Also the ball going in to the crowd etc and being held etc

Just have 5 or so balls behind the goal line, pick one up and go for it

If the ball goes into the crowd, there's no chance of a quick tap anyway, so it doesn't matter if the crowd hold onto it or not.

I guess this is a difference in preference, I'd prefer a player to win the right to a quick tap play, you would prefer the game to restart as quickly as possible. I think both are fair enough suggestions.

I'm not sure how this differs to Australia though?