Well the seasons don't give us much wiggle room here, so the thinking is to (1) make sure the sun has risen when you set off for work. If there's extra sunlight

Well the seasons don't give us much wiggle room here, so the thinking is to (1) make sure the sun has risen when you set off for work. If there's extra sunlight still, then (2) let's have that after work. In the winter, you can't have both, so you pick #1. In the summer, you have "extra" sunlight that's being wasted on the sleeping, so you shift it to after work and get #1 and #2.