Is this plan the "final"? They were saying last week that they wanted to coordinate with the EU regarding such measures. Did they ask anyone else what they think of this plan? I find the idea of the 72h testing rule unreasonable and even stupid! First of all there's no way countries "supplying" tourists to Greece will grant millions of tests for such a reason! Secondly, one has to consider that taking the test in itself is a process that exposes you to a considerable amount of contamination risk. Not by the needle or others instruments of testing obviously, but you have to visit a (closed) space, where there's guaranteed to be quite a few carriers around you....!

Edit: OK, I now read it a bit more carefully..
I'm pretty sure the "plan" will change...
​​​​​​Who is supposed to check the health passport? The airlines at the departure airport? Greek authorities at the arrival airport? Who will verify the authenticity of such a dokument? Will English be mandatory? Will they require hospitals to be the issuers or also private doctors and labs? I still see no way to actually validate authenticity besides a passport-like dokument with biometrics or a chip solution, both of which will come at a considerable cost, a cost to be added on top of the costs of the test itself!
Let's say a number of pax make it to the Greek airport without such a dokument! What will the authorities do with them?
And what if the foreign authorities decide to impose the very same rules and require all incoming pax to be tested within 72h of their departure? If you ask me, they'd be right to do so! There are simply so many holes, loopholes dangers, impossibilities and costs to this idea it is insane to even lay it down as a plan.