It's common for ebikes to be…

It's common for ebikes to be doing well over 30kph in the bike lanes, through parks, or in areas where motorized vehicles are banned. Police claim the law is too vague for them to enforce. Is there a way of wording these definitions so by-laws are enforceable?
(My neighbour regularly drives a moped-style ebikes with his wife, an infant, and 2 children under 6. Police claim they aren't sure if it's illegal or not)