Wouldn't it be better to tax all disposable objects in proportion to their impact on the environment or something like that? These single shot bans seem easy to go around.
Sure, the plastic Coke bottle costs 1-2 cents less than the glass one, but the ecological problems it creates are at least an order of magnitude higher than that.
If Coke can either increase their prices by $0.01 or $0.10, and the $0.01 option is preferred by consumers, their choice will be clear.