This is security theatre to placate the masses. Delta is already in every country. Vaccinated incoming travellers with recent tests showing negative results would have a negligible impact on total Delta infections.
Moreover, Delta is not a significant threat in countries where at-risk populations have been mostly vaccinated, which describes the US and most European countries. Infections != deaths.
Yeah, it probably won't be implemented in France or germany, i think we both have 80 to 85% of the population vaccinated.
Its a recomendation, not a law, and most countries don't follow EU recommendations. The reason it was drafted is because it allows small countries who want to ban US travelers without facing retribution "I'm sorry, its a EU recommendation, not our own will no hard feelings, please don't ban our imports".
By the way, this is used during PPP decision-making (find some obscure EU laws to veto some private partners decision, like using Azure cloud for AI4EU), and probably used politically, internally or externally to deny demands "No, it is impossible, the EU have a reco/law/designated standard on this" (And in 80% of the cases, this is non-binding).
I think this is the real power of the EU, giving politicians the possibility of deflecting blame. Most positive effect of Brexit for the UK is this imho.
The US, at this point, only has a slim majority of residents vaccinated - and all the evidence I've seen points to the fact that working age folks (those more likely to have a wide number of contacts in a day and those most likely to be doing the traveling) have mostly voluntarily eschewed the vaccine.
As a Canadian - we had trouble getting access to the vaccine for a long time - but we're closing in on 75% of the population vaccinated with vaccination rates only slightly beginning to taper off.
Moreover, Delta is not a significant threat in countries where at-risk populations have been mostly vaccinated, which describes the US and most European countries. Infections != deaths.