Why can't pharmacists change brand name to generic?

Today I sent over an rx for Concerta to the pharmacy. This is in Texas btw. 15 minutes later I get a phone call from the pharmacist at CVS. Pharmacist: Their insurance won't cover brand name, can you switch to generic? Me: Why are you calling me? Can't you switch it over on your own? Pharmacist: Well not really... Me: Fine then, absolutely, go ahead and change it to generic methylphenidate Pharmacist: I need your approval to switch it Me: Why? Pharmacist: I cant change it... Why can't pharmacists change brand name to generic?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums