I do know Coca-Cola was lobbying against mandatory returning of bottles against deposit in my country (Slovakia). It was already implemented in the 90s and no major increase of cost happened, but they didn't like it anyway. It's just usual corporate penny-pinching (and in your case, probably FUD).

In Germany collection of bottles has been implemented all the time and it is definitely not "very expensive". In Slovakia it is planned to start again since next year or so.