Your original post says 70% loss, i.e. 30% efficiency. In the context of an e-bike, to me, 70% efficiency is fine. It's a large bike and the majority of the power for the majority of users is likely going to be coming from the battery anyways.

Also presumably we should be comparing the efficiency to other ebikes not traditional bikes. I'm not sure how effective traditional ebikes are at integrating motor + human power together but I'd imagine there are some additional losses.