I kind of like the idea. I agree with breedmitch that asking “license please” can be sort of awkward, but better safe and awkward rather than sorry. The license will show the latest day of testing right? so it will give you a better idea of how “safe” your partner really is. Of course the method isn’t fool proof, but if your partner hasn’t got tested for a year or more, then you know something is wrong. Of course, this ID works best for people in one night stands etc. The best way to avoid this scenario completely is only engaging in sexual activites with someone you are in a actual relationship with.
So in summary, something is better than nothing, and i like the idea.