I walked almost everywhere with my big, coach built pram when my children were babies. If I needed to get back earlier - I set out earlier. I was very fit - all that walking - and my babies were very healthy - all that fresh air.
Of course people with buggies do need to travel by bus, sometimes, but don't the modern buggies fold flat? Are we talking about the large, ultra-padded things that seem to have replaced the pram, even for new-borns? I had a "push-chair" when mine were toddlers. Not plush and not particularly stylish but it supported their backs and it folded easily to fit on a bus or in a car boot.
Oh well, things change don't they? But I think life, in this respect, was less complicated for me than for today's mums.