I don't have any inside information about Robinhood's infrastructure, but I'd be willing to bet the mobile phone thing is a red herring. HFT will take that bet

I don't have any inside information about Robinhood's infrastructure, but I'd be willing to bet the mobile phone thing is a red herring. HFT will take that bet on the other side of every retail investor they can get their hands on, including those with very sophisticated trading terminals. For that matter they will take the other side for very sophisticated non-retail investors so long as its non-directional flow.