Unlike the development of things like MRSA and VRE - the flu shot is different.
MRSA and VRE developed primarily because of the over prescription of oral antibiotics. This allowed the existing pathogen to mutate and develop a resistance to the medication.
Flu shots are different - the vaccine is taken from an attenuated virus and harvested. So....it will protect patients from existing strains of the flu but not from new ones. Every couple of years a new strain will develop and thats when the drug companies get into a race to develop vaccines. So a flu shot will not really mutate an existing strain just supress it. The flu types though, can come from anywhere and usually carried by human to animal cross contamination, and the situation can be made worse with the availability of global travel. There are already a few strains of the flu that can be lethal and is out there. But, for the most part; a lot of it has to do with the handling of animals and as it's often seen it usually comes from more remote places then it migrates to more populated areas.
Being immunosupressed will certainly increase the chances for picking up bugs, but; there are a lot of very dangerous pathogens out there that can be picked up quite easily. Most people sweat things like HIV, generally; I tell them that Hepatitis is worse and easier to catch. There is a vaccine for that though. And , anyone can catch a Staph infection which in some cases can be dealdly or leave thr patient in lousy shape.
I agree that historically patients have recieved too much antibiotics, but; believe it or not Toronto, and specifically the Hospital for Sick Children has been a pioneer for alternate pharmacological models and use of antibiotics for pediatric patients. The right strides, in the last decade have been taken; but, there's still a long way to go.
It is difficult though - sometimes a first time parent will bring in a little one with a raging ear infection, the patient crying their lungs out...but all the doctor can say is to ride it out for 72 hours because of the mandate against overprescribing antibiotics. The parents usually take a fit with this piece of information. Most ear infections with kids will subside in 72 hours. But if you were the parent, can you handle a screaming infant or toddler? Hard to say....thats why some family doctors, specially the old timers; feel compelled to give antibiotics.