“AG Barr, the maker of Irn Bru, warned that “the scope for fraud in a Scottish DRS [deposit return scheme] is huge. On a small scale we could see people scavenging in bins for containers, as is the US experience. On a medium scale there is the potential for local authority amenity centre looting. And on a larger scale there is the very real possibility of cross-border trafficking of deposit-bearing containers. It costs around £400 to move a lorry load of cans from England to Scotland. A single lorry could carry 160,000 crushed cans or £32,000 worth of deposits.”” https://www.theguardian.com/environment/2017/sep/05/scotland-planning-deposit-return-scheme-for-bottles-and-cans
And on a massive scale, there’s combining the health hazards of refined sugar, carbonic and citric acids, artificial flavourings, preservatives and colours, and rust into a multimillion pound business.
“A spokesman for [SEPA] said: ‘Our officers are comfortable that there is no environmental risk to the River Cree as a result of the bottles being released and, following inquiries, understand almost all of the bottles were contained and removed from the river fairly quickly by local residents.’ …
‘It was never my intent to harm the environment. It was more accident, naivety as well as stupidity in the execution. … It was just my intention to send a wee love bottle with a message to someone I had not yet met.'” http://www.bbc.co.uk/news/uk-scotland-south-scotland-40738484