> it's not like the random people working there had any choice in the corporate policies or autonomy to choose to make the chicken in a different way.
I'm torn on this one, and can see both sides. For any kind of mega-business, not just restaurant chains: If your goal is to correct corporate behavior, protest or "make things difficult for corporate" then there really aren't any good options. You could annoy the individual stores and/or frontline staff, but as you say they are usually powerless minimum-wage drones who can't change things, and even might probably be sympathetic to your cause. On the other hand, if enough people make the businesses unpleasant or do things at those business that end up costing corporate, there is a slim chance that corporate might make changes.
A big problem with mega-business style capitalism is that key stakeholders like employees and the general public are powerless. You can only change a business's behavior if you're either 1. shareholders or 2. customers via boycott or 3. regulators. Unfortunately, the non-customer general public cannot vote a corporation out, nor can they walk into their local WalMart and "complain to the owner of WalMart" like they can for smaller local businesses.