The idea that a company with billions of dollars in annual revenues has law firms running around in multiple states filing lawsuits on its behalf, and paying copious amounts of attorneys fees to those law firms, without being aware of, much less directing what they are doing, is laughable.
Rule 12 of the Texas Rules of Civil Procedure allows any party who believes an attorney is acting without authority to file a motion and require the attorney to show proof that they are authorized to act on behalf of the client they purport to represent. In other states, or Federal Court, a motion to strike pleadings alleging the attorney was not authorized to file them, amounts to the same thing.
And once litigation is commenced, and discovery begins, the client, Buc-ees, will have to swear to discovery responses, and produce corporate representatives for deposition.
It maybe that Buc-ees has authorized law firms to send nastygrams to businesses who might be violating their trademarks, but Buc-ees is absolutely aware of, and directing, every lawsuit brought on its behalf.
You don't believe it is possible that a lawyer assigned to protect the company's trademarks could simply walk into his superior's office and tell him that Beaver's market is infringing on their logo and be told to send them a cease and desist letter and if they fail to immediately comply file suit?
A firm that takes an aggressive line to bill more hours is going to take on all comers. The company take employs such a company gets what they pay for and doesn't care.