Well, IF there is no checking that its an approve lab, which I still doubt, that probably possible. But honestly if no one is checking, you could probably find a crappy lab to do the same thing, right?
STILL easier to right click my card photo above, print and write your name on it.....
You are making the assumption that they are checking everything against a list of approved labs, making sure that the URL is correct vs just looking for the no status. Most airlines reps seem more concerned about getting through the line then trying to root out fraud.
Yes the vaccine card is easier, but the test fraud isn't impossible either. In either case worrying about it is spending time gnashing your teeth over something fairly minor we concentrate on what is important, getting the vaccine into the vulnerable, followed by anyone else that is willing to take it. After that we should largely be able to go back to normal.