They're doing that in Germany for example. But as they use a vaccine passport for lots of things, the idea is that you can either get vaccinated for free, or pay for an LFT to get in somewhere. Don't think they have started to implement it yet, so no idea if it works.
You can still get LFT tests for free in pharmacies and other places in Germany at the moment, but this will be discontinued from mid October on I think (I would need to look up the exact date; I am double jabbed and so is everyone in my immediate family and among my friends and co-workers, so didn't really memorize the date).
This is supposed to help encourage more people to get vaccinated. The argument is why should the general public pay for free tests (they are financed by the state, i.e. through taxes) for those unwilling to get a jab when said jab is free. Of course people excempt due to medical reasons will still get paid tests, it is only to hit the anti-vaxxers. Free of charge testing made sense as long as there were no vaccines or not enough, but these days you can get jabs pretty much on the spot in many places (GP, shopping centres, public transport in Berlin and so forth).
More federal states also allow the optional 2G model now. I've posted about the German 3G/2G models a little while ago. Businesses can decide to accept customers who are vaccinated or have had Covid only. Tests are irrelevant. I walked past a restaurant in Frankfurt's city centre yesterday, small Thai place, and a guy sat down on one of their four tables outside and the waitress approached him and said "do you have your vaccine certificate with you", and he said "no" and then she went "then I am afraid I cannot..." and I had walked past at this point, but I suppose she said she could not serve him, cause when I looked back I saw him get up and it looked like he left.
