It looks like a solution to something that isn't really a problem. . Aka, government overreach. The EU spent their time mandating this? More and more I think the EU was a bad idea.
The problem: Europeans consume about 140 single-use bottles per person per year; each cap weights ~2 g, making it 126,000 tons per year for the 450 millions EU residents; Everything that does not go to the city trash ends up in rivers and the sea; caps are frequently discarded to the ground. Keeping the caps with the bottles saves many tons of plastics from the oceans.
Not overreach: Legal ground is the United Nations Convention on the Law of the Sea, which requires Signatories to "ensure environmentally sound waste management to prevent and reduce marine litter from both sea and land sources."
What the EU did: The EU did not wake up one morning and decide to mandate this. It is though a Directive. These happen when several Member States decide to regulate the bottle caps, and request the EU to "harmonize", which is to publish a common legislative ground that simultaneously apply in the 27 Member States, rather than each of them taking steps in different directions.
Why the EU is a good idea: The EU makes possible coordination of policies at the level of the 27 Member States that would not otherwise be possible. It avoids waste associated to the production of bottles to different standards; it allows better exchange of goods within the Internal Market since all bottles are produced to the same standard and can freely circulate.
References:
* Directive 2019/904: https://eur-lex.europa.eu/lega...
* Lay summary: https://eur-lex.europa.eu/EN/l...