Ontario (Canada) has a very controversial and much criticized (especially by motorcyclists) proposed law (Bill 117) that would outright ban passengers under 14 on motorcycles.
Currently in Ontario all passengers on motorcycles (as the rider) must wear an approved helmet. To carry a passenger on a motorcycle the operator must have at least the second level of license (an M2) and the bike must be equipped with a proper pillion seat as well as foot pegs or boards on which the passenger's feet will rest. This implies that riding in front of the operator is illegal, as well as ensuring that if it is a child they are large enough to reach the pegs.
Besides the above sensible "restrictions" already in place, as a motorcycle rider instructor, a motorcyclist for many years, and a grandfather with young children that I enjoy taking for an occasional ride, I would also propose the following restrictions: First, the operator in the jurisdiction of Ontario should be required to have more experience than just an M2 license if they are to take any passenger, especially younger ones. Second, I would insist on more than just a motorcycle helmet be worn by young passengers - proper gear should include a jacket, heavy pants, gloves and ankle-high boots. (I know that sounds cumbersome, but every motorcyclist should be wearing that gear, and young passengers are the most valuable to protect.) Finally, for young passengers (maybe under 14 is the age) the motorcycle should be equipped with a passenger backrest and provisions made (other than just holding-on to the waist of the operator) for handholds. (A "buddy" belt worn by the operator with hooks for the passenger to grasp is one device - besides "rails" or handholds on the actual bike. The straps commonly found on motorcycle seats are NOT appropriate, in my assessment.) That's how I want to carry young passengers on my motorcycle, and that's even how my wife insists on riding with me.
Let's hope that the draconian Bill 117 in Ontario dies on the committee floor!