> too many cars
they are probably right and I can certainly bet my money there are way way more cars in small EU country than there were 30 years ago (assuming you had her at least at 30, if later, then the difference will be even starker)
my kids school is ~1.1km walk, son is walking to/from school by himself maybe from 3rd grade (8.5yo) with classmate(s), I still walk my 4th grade (8yo) daugher to school in the morning (unreliable/inconsistent slow classmate living nearby), at least I get some exercise working from home (if I didnt have time to walk them and help them with backpacks I would probably let them go by themselves earlier)
the main reason I still walk her is crossing the road, because I consider Prague roads dangerous even for adult pedestrian, let alone for kid, too many crazies driving here cars
other big reason is heavy backpack when they have to lug tons of books/workbooks
on the way back they go home either with classmates or together already for years, used to pick them up only in 1st and maybe 2nd grade