I generally walk to school to pick them up, but there's been a few times this year that I've been unavaliable so DH has WFH and my y4 and y6 have walked all 300m and crossed one suburban estate "main" road together and let themselves in to a house with a parent.
Most y6s are now walking themselves or walking at their own pace while parents collect younger siblings. Some start from y5.
In 5 months DS1 will be a mile's walk from the bus stop and 3 miles bus from school. Depending on how his confidence is (he has ASD and it's confidence rather than ability) he may need me to do that walk with him and that might mean DS2 having to walk himself to/ from school in y5 as his journey is safer than DS1's. I'm happy with his road sense and we regularly discuss the safe crossing points/ views. I also let him make the judgement on crossing and let him do supervised solo crossings.
In the 80s/ 90s, I lived out of catchment so was a teenager before being allowed to walk/ bus. DM was overprotective and only gave up on driving me to school when forced by a broken bone. I'd have happily have done it years earlier.
My infant school had parents come to the playground. Moving school at 7, (late 80s) the next school had children come up the drive to be collected at the road at infants and juniors.
I remember in y5 (early 90s) one girl had a key on a string like a necklace. A lot of the mums were SAHMs or worked rather part-time and were able to pick up. There was no childcare provision based at school, some children went to childminders.
What I'm finding tricky is the culture (or lack of) in letting children have those early tastes of independence. It's a quiet, "safe" neighbourhood and juniors years did used to play out more 10-15 years ago. A lot of children simply aren't avaliable either in childcare or formal activities. Mine are small and young looking and would look conspicuous being allowed to play out even though there are safe places on our doorstep.