The underlying issue here isn't education and regulation of the folks who sell chickens, or other pets.  It's that you have two types of people buying chickens - Type 1 is folks who believe that animal lives have intrinsic value regardless of how much it cost them to purchase or obtain the animal, and that animals deserve to have their needs met and to be cared for in a species appropriate way.  Type 2 is folks who do not believe these things.  The second type of people may believe that animals are disposable, may value them according to how much money they paid for them, or may believe that animals are only around to meet the people's needs - it really doesn't matter what this second type of people believes, because they DON'T believe what the first group of folks do.
These two types of folks come into the pet store with their views of animals already fixed.  No amount of education or salesmanship (especially with the limited time and resources available in a store environment) will change the underlying beliefs of these two types of people.  Type 1 people will be trying to care for their chicks the best they know how because it's the right thing to do.  They may be uneducated and uninformed and impulsive, but in most cases are willing to be educated, and quickly become informed, because they care about taking care of their animals properly.  Type 1 people may be impulsive purchasers of chicks, but they'll walk out with the chicks and a beginning brooder kit, food, shavings, heat lamp, etc. because the salesperson recommended it, they recognized they didn't know much if anything about caring for chickens, and they wanted to learn.  They may make mistakes out of ignorance and inexperience but learn from them, and don't repeat them.  
Type 2 people will do whatever they want with their animals and feel no guilt about it.  No amount of education or assistance will help these people because they don't want help.  They already know everything and if something messes up, it's always someone else's fault.  No amount of laws and regulations are going to make Type 2 people care about the animals they abuse, because the laws never apply to them, only to other people.  There is no way to regulate these type of people into being decent people.  It just isn't possible.  The best we can do is try to protect others from their bad choices, but doing that without stepping all over everyone's rights is extremely challenging.  
With our current social norms and political structures, laws and regulations about chicken purchasing will only make life more difficult for the Type 1 people.  Type 2 people will do what they want to regardless.
The underlying issue here is much larger than regulating or lack of regulations in chicken purchasing.