That's a ridiculously low expectation. My older daughter took the bus alone to school by herself when she was 7 (and was immensely proud) and took her little sister with her by age 9. We live in a country with much worse public transport now, but she is walking back to and from the swimming pool (Abt 2km though the city).

I believe giving them independence and trusting them early is the key to success. It's actually much easier now then back when we grew up, she just got a kids smart watch (her request) so she can call if there is something wrong, we never had anything like that (if we were lucky there was a public payphone)