David from Xapo &/or anyone who can answer this:

In doing my due diligence and checking out the feedback on Xapo first, I'm seeing that it seems to be a favored wallet for Faucets.  Some, like Moon Bitcoin, make direct deposits to Xapo wallet while those with other wallets have to wait until collection day.  I'm curious.  Why is this? 

link for moon bitcoin is http://www.moonbit.co.in/