Suppose there are two employees: Alice and Bob, who do the same job at the same factory. Alice has a 10 minute (20RT) commute, Bob commutes 35 minutes(70RT).
If you’re the owner of the factory, would you compensate them for their commutes? How would you do it?
No. It’s not the employers fault that Alice spent more money on her mode of transportation.
This is why paying people for their commute is unreasonable. Payment by mileage is based fuel costs mostly. Some wear and tear, but mainly it’s to offset the fuel cost. If someone rides a bike to work, they don’t have fuel costs, therefore should not be compensated.