Most of our riding hereabouts is on what you refer to as asphalt lanes.
We only do walk and trot on asphalt but rarely canter.
Most of our horses are shod together with studs inserted at the back of the shoe to assist with grip on the hills both up and down at both walk and trot. On lanes polished by car tyres, especially after rain, slipperyness is an issue.
In our opinion cantering on a continuous hard surface involves significant concussion to the horse's hoof. It is to be avoided for more than a few yards.
Also if you need to stop suddenly from the canter speed, the shoe has nothing to grip into even when fitted with studs.
on a downward sloping hill, if the horse in fright or cussedness decides to bolt and go from canter to gallop - then the horse can't stop until it reaches level ground - regardless of what traffic may be coming up the lane.
In Britain we share access over narrow (car width) asphalted lanes with other traffic ie cars, tractors, trucks, dairy cows, bikes and pedestrians.
So any pace above an extended trot is seen to be too fast.