We didn't have a car. The buggy made it possible to drop off the eldest at school, bring DD2 back safely instead of having to dodge the Range Rovers bumping up the kerbs at speed, go to pre school, come back, pick her up from pre school, go to the shops (a useful learning experience for DD2 in terms of food, communicating with people, following her own visual shopping list, widening the foods she'd eat, numeracy, literacy, etc), get the shopping into the buggy, then collect DD1 from school, survive the 2.30-3.40 pavement parkers on the main road before DD2 would get out at the bottom of the hill and we'd go home via the woods/the park/the sweetshop/etc.
Once DD started at the Nursery class, the day was slightly flipped in that I'd have to drop off, do some activities/house stuff, then lunch, then Nursery, then shopping without DD2, then come back to pick them both up instead.
DD2 was one of the fittest, healthiest and fastest children in her Nursery class (just as DD1 was in her year) because we did so much walking, carrying and generally going places without the luxury of just piling into a car. But it also meant potatoes, cat litter, food, washing powder and all shopping in general had to be carried and walked up that hill, which the buggy helped massively with, what with being disabled due to autoimmune and joint issues - and I didn't mind being fitter, but I certainly would have objected to being thought as lazy because I didn't force DD2 to walk or use a scooter to roll herself into a grazed heap down the steepest part of the hill or straight under the wheels of a 4x4 whilst I carried shopping, school bags, a lunchbox, coats, PE kit, swimming kit, book bags and all the other bits of child related paraphernalia for considerably further than where the cars were abandoned parked for easy access.
Well, that and whilst going 10 yards from a car to school may have been doable in pissing rain, sleet and snow with an umbrella, it was a whole different prospect for a 3 year old without that - and the rain cover was very useful, as it kept her dry and warm whilst waiting the inevitable 10-20 minutes after the scheduled KS2 end time for DD1 to be let out and then having to walk home.
The last time I used a buggy was the day they broke up for Christmas when she was 3 and a half - I'd just bought a load of heavy stuff and knew I wouldn't be able to carry it as well as everything the girls were bringing home, but for the first time in weeks, DD2 climbed straight in because she was tired.
I'd probably mention the fact that the letter implied having additional needs was something to be ashamed of/they should be worried that people might think that of their children, would potentially be disclosing a child's personal medical information 'if you see a child in a buggy, that means they have SEND' and that it would create negative feelings for people who were unable to afford a vehicle or had a disability that meant they were less able to carry things or sprint after/carry small children in an area made less safe by the numbers who drove.
And the posters on here sneering at the thought that using a buggy might be a solution for a problem they have the privilege of never experiencing (ie, poverty/disability) should take a long, hard look at themselves, especially if they actually work with children.