People not used to it. On my school run some will do 20-60 depending on where along the road and how narrow and what the sight lines are. Others will just do 20-30 for the whole 10 miles.

At a couple of locations there’s morning room but lots of room to overtake (as long as nothing comes the other way), the road is nearly wide enough to have a line down the middle. Most drivers are fine but some of the 20-30 lot will swerve all over the road to try to block overtaking.

These aren’t super narrow, you can get a tractor or hgv down the whole road, and even at some passing places get one past another.