[SavvyGuard]

I found a similar question on Quora [1], with an answer by an ex-quant. It seems to boil down to tradition and bureaucratic inefficiencies by the involved parties. So I agree, this makes the whole liquidity argument seem weak.

[1] http://www.quora.com/In-the-24-hour-world-why-do-the-New-Yor...