You do have a point there. The EU is pitching COVID certificates as a way to restore travel in the bloc, but I can’t imagine they will be used in places other than airports/bus stations/train stations.
The issue is that maintaining roadblocks along Schengen borders has incurred costs that countries don’t like to deal with long-term, and even with the roadblocks there have been a lot of gaps. I spent last summer cycling across Europe. I was fortunate in that all borders on my route were open, but I met a load of other cyclists who had crossed various Schengen borders illegally, because no one was checking traffic along some minor road through the fields.
So, for people with their own transportation, you might manage an entire European summer holiday without anyone ever checking your COVID certificate.
Denmark use a similar app called “Coronapas”. Works similar to the Swiss one, displaying latest test results and vaccine status. It’s currently required to enter any restaurants or public spaces and has been very successful in returning some degree of normality to the country. Singapore are trialing a similar solution where the “Trace Together” app displays my vaccine status, possible exposure as well as test results. Very efficient.
Different countries, different traditions. The US seems quite opposed to federally enforcing vaccine registration and passports, yet they find it ok to conduct mass surveillance of its citizens (and foreigners). On the contrary, Germany have strict privacy laws; yet they push for digital vaccine passports.
"It’s currently required to enter any restaurants or public spaces and has been very successful in returning some degree of normality to the country.", there seems to be a link between the app and the normality in this statement, but there actually is no link between the two: an app like this may have some impact at some longer term, to lighten another wave, but it doesn't have any effect on the current re-openings.
The Danish strategy is to test a lot of people and catch new cases early.
Requiring a green corona passport when entering various establishments where transmission can happen, is both a way to decrease the chance of transmission in these places, and to force more people to get tested, to hopefully catch asymptomatic people before they infect too many other people.
The logic is that it's not the reason for reopening, nor its success: it will be successful in a few months if there is no next wave, or if it is not as high as some other places where such a thing will not be in place.
The reopening is possible because of previous actions, and its result will only be seen in a few months.
Denmark is an outlier among EU countries in using an app for internal travel and activities. Many other EU countries have already reopened their restaurant sector without requiring any proof of vaccination.
We are using IDEMIX to enable the DCC and COVID testing to be used all over the country. This allows us to only disclose a tiny amount of information - in many cases just one of your initials an either your month or day of birth - whilst proving yourself to be low-risk for COVID.
The DCC itself contains a lot of information so it shouldn't be directly used outside of border or police checks. I can - technically - be used as the basis for issuing of Verified Credentials by other parties. For example by airports - with the privacy protected by their privacy policy.
Whether the law allows that is another question.. and IANAL..
[Disclaimer: I work on the Dutch COVID apps and am deeply involved with Digital Green on EU level].
While the technology you are developing may allow that proof of COVID status, as the OP mentions, it is questionable if it will actually be used broadly in many countries. When countries have already reopened their hospitality sectors to all regardless of status, then they may be loathe to begin requiring COVID proof. Nor do hospitality staff necessarily want to given the duty of checking statuses.
So if COVID status proof is required country-internally over the coming months, in many countries it will probably be used for mass events (e.g. the UNTOLD festival in Romania) but otherwise not.
The issue is that maintaining roadblocks along Schengen borders has incurred costs that countries don’t like to deal with long-term, and even with the roadblocks there have been a lot of gaps. I spent last summer cycling across Europe. I was fortunate in that all borders on my route were open, but I met a load of other cyclists who had crossed various Schengen borders illegally, because no one was checking traffic along some minor road through the fields.
So, for people with their own transportation, you might manage an entire European summer holiday without anyone ever checking your COVID certificate.