Hi @arg26 great question and as ever @alexs is on the money! Although the 
birth place is London and we have a UK banking licence, we’d love to give people around the world help managing their money. One way to do that is getting a banking licence in lots of jurisdictions, or partner with a US bank, or maybe find a way to WhatsApp banking i.e. do it irrespective of the regulatory jurisdiction.
Right now it’s important we get our ‘restrictions’ lifted in the UK on our banking licence (to hold unlimited deposits and lend) then we will turn our attention to other markets like the US. That aside, all the points you make are valid, but none (in my opinion) prevent Monzo or a Monzo-like bank operating in the US.