This section does not apply to service rendered or commodities furnished: to the officers, employees, pensioners, and immediate family members of the officers, employees, and pensioners of a public service company; to the United States, the State, or a local government; to provide relief in cases of general epidemic, pestilence, flood, or other similar calamity; in the case of common carriers, to transport: personnel of another common carrier that reciprocates for personnel of the transporting common carrier; hospital patients; indigent, destitute, and homeless individuals; persons exclusively engaged in charitable work; residents of federal or State veterans homes, including those about to enter a home or those returning from a home; railway mail service employees and baggage agents; post office, customs, and immigration inspectors; newspaper vendors; property for exhibition carried to or from fairs and expositions; employees of sleeping car companies, express companies, telegraph companies, and telephone companies doing business along the line of the common carrier; persons and property incident to or connected with contracts for construction, operation, or maintenance of the plant of the transportation company, to the extent provided in the contracts; individuals injured in accidents and physicians, nurses, or other necessary caretakers attending the injured individuals in transit; children under the age of 5 years for no charge; children under 12 years for half fare; or persons at free or reduced rates that are otherwise authorized by law; in the case of common carriers, for the issuance of mileage, excursion, or commuter tickets; to free steamboat excursion transportation from May through August of each year, from Baltimore City to any place in the State, in exchange for services rendered in advertising the excursion business; to obtain essential data by a method that uses a limited sample of customers, in connection with a rate structure study conducted under formal proceedings before the Commission; to telephone lifeline service provided to eligible subscribers under § 8–201 of this article; or to electricity or gas service provided to eligible limited–income customers through an approved limited–income mechanism under § 4–308 of this title. For any service rendered or commodity furnished, a public service company may not directly or indirectly, by any means, including special rates, rebates, drawbacks, or refunds: charge, demand, or receive from a person compensation that is greater or less than from any other person under substantially similar circumstances; extend a privilege or facility to a person, except those privileges and facilities that are extended uniformly to all persons under substantially similar circumstances; discriminate against a person, locality, or particular class of service; or give undue or unreasonable preference to or cause undue or unreasonable prejudice to a person, locality, or particular class of service.