It's not just the problems with the system, it's the whole "computer says no" attitude that people dealing with the unwell have that gets people furious. There's several on here with chronic conditions, and their experiences in getting treatment or their medication would try the patience of a 21 year old Saint.
Incidentally, I worked in a pharmacy for four years in the 80s and never saw any old people being rude. So it seems to be another of the trends that started when everyone became slaves to process and procedure.
I deal with a lot of pensioners and get rudeness extremely rarely. So if people are constantly rude to someone I'd say they need to look at their own manners.