probably not the only reason, they also interest on that $100 until it is time to pay out. If google would say how much that interest is according to every account up until the time they pay out, then I would bet you that would be a chunk of change. If you have the technology, then you can verify accounts any number of ways to combat fraud.... the only reason I see it at $100 is because google makes interest until payout....
I'm not sure. I've never used AdSense, but I'm sure there's a good reason. And it most likely works to benefit them in some way.
In my opinion, with $100 in clicks - they will have more data to determine if the clicks are valid. More data = better accuracy when banning accounts. Maybe this will deter all of the Google forum posts that start with, "I bought traffic from Fiverr and Google Adsense banned my account - What did I do wrong!?"
Maybe they should have read google's TOS concerning using automated traffic. Sellers have been pushing that traffic crap on here for years. buy my traffic, i assure you, my traffic is google safe; no traffic that you have to buy is google safe, period.... I think that is clearly spelled out in Google's Terms, and it is nothing new....
Wire transfers can be very expensive. I have to charge my customers $50 per international wire transfer just to cover the costs my bank passes on to me. That is not including what the payor's bank charges him. Most of that $50 gets paid by my bank to other banks in the wire transfer chain. My bank only charges $14 for domestic wire transfers and they keep it all. Needless to say, I STRONGLY discourage my customers not to do a wire transfer as there are many many cheaper ways of paying for stuff.