I don't agree with the practice at all, nor am I defending Doctors at all - but this all began when malpractice lawsuits started when people were hurt/injured/killed from not being prescribed antibiotics when they actually needed them.
If a Doctor has to make a decision between prescribing or not prescribing a strong general antibiotic for something with rather generic symptoms, many close to other diseases (both viral and bacterial), then he's going to go the socially irresponsible route and prescribe them. In his/her eyes, it's cheap insurance for a malpractice lawsuit.
If I remember the stats correctly: cattle and other livestock consume around 30 million pounds of antibiotics per year in the US, while I believe humans consume around 6 million pounds per year. We are creating a perfect storm (or soup) for superbugs.
I can only imagine that HRT ignorance among doctors must is extremely prevalent. Try telling most docs information you know and they try and write you off like you dont know what you're talking about - that one gets me the most.