(a) A person commits an offense if he owns or allows the display or use of any tobacco-product vending machine upon any property within the city.
(b) It is a defense to prosecution under Subsection (a) that the tobacco-product vending machine was:
(1) situated in a premises where entry by a person under 21 years of age is prohibited by law;
(2) situated in a hotel, motel, bar, or restaurant bar,
(3) located in a workplace with the permission of the employer; provided that:
(A) the employer usually has no person under 21 years of age employed at the workplace; and
(B) the tobacco-product vending machine is situated at a location within the workplace to which no person other than an employee of the workplace is usually permitted to have access; or