Catrike Speed rider, Miles, has worked out a great system for getting in and out of his very low and laidback recumbent trike using a strap attached to his roof-rack.
A hub-driven electric-motor such as Bionx, Neodrive, or GoSwiss needs an anchor point that is physically fixed on the recumbent trike or bicycle, so it has something to push against. Without this anchor point, the hub would simply spin when activated with electricity.