Indeed, and most cattle are kept in herds so if you have an infectious something then it needs to be addressed quickly before it spreads through the herd.Uhmm no they are not just pumped full of them, you know it costs a fortune right? Do you think farmers are rolling in the money? They are generally given it if they present symptoms, in some circumstances they might give it to other cows within the herd if one or more show symptoms.
It's like people thinking that crops are just sprayed willy nilly with pesticides, farmers already have small margins they can't make them any smaller.