It sounds like Irn-Bru was only viable _because_ of the sort of people who drink >100 litres a year. You were benefitting from that viability thanks to the very people you admit were being targeted by the tax. If they had stopped their high consumption for some other reason, availability of the original Irn-Bru would have suffered the same result due to the same drop in demand. The tax isn’t directly to blame here. The direct cause is the original motivation itself, regardless of how it was implemented. Considering only this specific example you cannot reject the tax without also rejecting the motivation.
