We do not implement these measures here (Germany) at the moment. Anyone can visit stores or e.g. retirement homes without having to show a negative test result or proof of vaccination. Before easing the measures, people with proof of vaccination were treated like having a negative result in general, i.e. they could do all the things that others also could but without the hassle of having to be tested.
We have the vacciness, anyone can get one for free, just open up, and let the antivaxxers risk it if they want.
Even with a vaccine you can get COVID. Any body hosting a COVID virus is an environment where mutations happen.
We don't just want people to stop dying from COVID. We also want to stop new more dangerous strains of the virus to emerge or propagate.
If you are vaccinated, you just show your pass and go into the bar. If you aren't you have to produce a test. A recent test. So frequent renew. Or you might just not be allowed to get in.
So just get the vaccine and life will be easier.
If you don't want the vaccine, just stay at home.
The QR code by itself is not proof of anything until you have verified that it actually belongs to the person showing it. That's where the ID comes in.