Depends on the e-bike. I ride a 15 mph e-bike and figure it's a lot safer than my former 60-85 mph motorbikes but it's mostly just a function of speed. The motorbikes were more stable at 15 mph than the e-bike, especially the enduro one which could go over kerbs, logs, ditches without blinking much.

Maybe we could improve safety by requiring e-bikes to be built like enduros but with the 15 mph thing? (bike pic https://en.wikipedia.org/wiki/Enduro_motorcycle)