depends on the child itself and the distances you are walking, imo.....I truely beleive that some of those...don't use a Buggy when child is that age people, actually possibly use a car for trips that I would happily walk, partly with children walking (ys 3 and ms 4 1/2) and partly standing on the back or sitting....
Anecdotally, my es was really lazy and still using a Buggy age 3, but we were living in a hot country and walking any , to us, closer distances, and I haad people moan at me then, but then said to them, but look, you actually drive from there to there if you have Kids, which they did, and that soon shut them up...
also, we got rid of his Buggy when he was 3 1/2, as we moved from Cyprus to UK, well, it was no problem then, however, a lt of trips I otherwise may would have walked I did drive...so really, he didn't walk much more for a fair while...age 11 he is a fine walker, lol....