It's not economic to have the overhead of writing out hundreds and thousands of very small cheques each month.
It's not economic for me to have my money sitting in a Google bank account making Google money. I much prefer getting less of a commission if I get paid sooner. Do the math – say I get 20 clicks a day at say 2 cents a click, that’s over 8 months between checks. During those eight months Google will have made money on my money. At 4% Google will have made over $18. Then multiply that by say a 10,000 small sites like mine and then Google has made over $18,000. This part of the business plan.