I reckon it's equal between scooters and motorbikes for safety or otherwise.
The riders, however...
As far as newbies/experienced riders are concerned...my money is on newbies being more dangerous. They are constantly thinking about what is happening right now in front of them, along with trying to control a machine they are not familiar with, as well as remember all the road rules etc. Because they cannot effectively do all that at the same time, PLUS be aware of all the stuff 10 seconds ahead/behind/to the side etc...and often they have poorly maintained bikes...this makes them unpredictable and difficult to gauge when your paths cross (so to speak).
Do you realise how many holes there could be if people would just take the time to take the dirt out of them?
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