Should motorbikes and cars share lanes? How to deal with left turns (the dangerous ones) in junctions? Should motorbikes and bikes have to do two-step left turn?

There’s an idea that we should categorize vehicles as human-poweres or not. Is this a good idea? How about paddle-assist-only ebikes?
When there’s not enough space for lanes, which type of vehicle get compromised?


What if we put islands in the middle of the intersection and turned it into a roundabout. Lanes would be narrow so cars would have to slow down, and it eliminates the left turn problem and keeps bicycles from having to stop.