In the case of SIN scanners, you have to ask yourself what the scanner is interested in verifying. Assume that not everyone can afford top-notch scanners, and that they have to make a lot of sacrifices. Stuffer Shack and public transportation for instance - they only care that they make a perfunctory scan. They make a good living off the SINless after all. Assume no more than a 1. A 2 in high-end neighborhoods.
A high society club will primarily be interested in verifying that the SIN belongs to a member. Assume a higher scan up front than afterward, probably a 2-4 up front and then just a 1 after that to verify the ID exists.
Boarding a flight will require top-notch security (which is why the TSA doesn't exist anymore! bazinga!) so they'll likely be scanning at least a 4. If you're doing a sub-orbital or some other rich folk ride, expect a 6.
Police checkpoints will vary by neighborhood to some degree. Bellevue would likely be a 4, while downtown would likely be a 2. The Ork Underground won't even have a police checkpoint (depending on your timeline).
The way I handle licenses is to restrict their rating to the rating of the SIN. Then I have the scanner look for the lower of the two. If the license trips up the scanner, it re-scans the SIN. If the SIN trips the scanner, then the SIN gets burned.