>And audible != loud

People who sleep with the windows opened in summer at night(most Europeans) facing the street where vespas are driving would beg to differ.

Then there's the separate issue that some(many?) owners either rev their vespas for more power(maybe due to worn belt) or they just fuck with their exhaust to squeeze more power at the expense of noise.

Either way, there's plenty of good reasons people find mopeds/scooter overall far more noisy and annoying than cars.