I saw an article on the Independent web site recently discussing the dangers of renting when on holiday overseas, see here. The Guardian reported almost the same sad facts. The articles report that of course when you go on holiday your defences are down and you are vulnerable to accidents given that you do not know the local road uses and customs and on two wheels you are very exposed to everything.
This was evident to me without reading these articles. On the Amalfi coast there are many scooter rental companies and so in the summer months you can see the visitors buzzing around the place. In all cases the uses are given a helmet of course, and then because of the heat they dress for the beach so shorts, t-shirts and flip flops. And of course these small scooters are either 125 or 150cc so they can get up to 80kph, and given also that most renters are not experienced riders then you have a dangerous and explosive mix, bringing danger.
The roads along the Amalfi coast then make their own contribution, as the roads are narrow, potholed and in the summer months carry alot of visitors as well as commercial and local traffic.
I therefore conclude that only experienced riders should rent these bikes and then wear at least jeans and a jacket, so that a small spill does not have serious consequences!!