Taxation works, but only when the product cannot be changed. A cigarette, is a cigarette , is a cigarette. You cannot swap the tobacco for straw or other substitute. Plstic bags likewise.
The problem with taxing food stuffs is that it has ramifications. The tax on sugar has not just meant that the manufacturers have reduced the amount of sugar in drinks and they are now less sweet. Manufacturers have replaced the sugar with sweeteners and, I have read, that many soft drinks are sweeter than they used to be.
The purpose of the sugar tax is to break our addiction to sugar, but that will only happen when we break our addiction to sweetness and the current sugar tax does not do that so it so like watering plants in the rain.
The other problem, and I admit this is a personal grumble, is that I am among the many people who can always taste sweeteners in a product and dislike the taste. Since the sugar tax, I have had to stop drinking soft drinks and have several times ordered a drink and then not drunk it because the smell or first sip tells me it has sweeteners in it.
All it has done, is led me to drink more alcohol! Because before when we went out for a drink I would order a soft drink, now I order a beer or lager because there is no way of finding out whether any soft drink a pub serves will contain sweetener or not.