Everything has to be taken in context though!
Whilst it is horrid that her disabled parents had the vile note left for them, I have seen plenty of people park in P&C parking that are fully able bodied, no children. I complained to my local tescos when a couple (40's - 50's) took the last parking space both walking well etc.. and was told there is nothing that could be done! For me I don't car particularly if its near the store I just want more space to be able to get DD in and out of the car without scratching my or someone else's car!
I think that in my supermarkets local to me they have made the general spaces smaller than they used to be so if you don't get a parent and child space and cna't find one miles away it can be a pain! but I would never expect an elderly or disabled person to have to walk far from the store likewise I wouldn't resent them parking in a p&c space!
Ref buggies I have to agree its not the end of the world if you have to fold your buggy for godsake if you can't be asked to walk then you have to accept that it might not be able to stay up!
Ref the buses and tubes I always offer my seat up even now to anyone who looks like they are struggling/elderly/pregnant (even though I pg myself if they are further on than me!).
I remember commuting to work on crutches with a broken ankle and never getting a seat offered to me!
Being a mother 10yrs ago had to be a lot different to now, instance I bet not both sets of parents worked full time as much as they do now! Childcare and train travel has raised consistantly higher than inflation/salary increases.....also house prices are considerably higher!
If we'd had children 10yrs ago i probably wouldn't have to work full time!