Thermal printers cannot put tracking information on the paper because they don't use ink. The paper itself is specially treated, and by heating parts of the paper the paper is marked. Thermal paper has very limited options when it comes to it being marked. High jinx like the deal with the laser color printers and tracking dots would be way way harder to pull off with thermal paper. I'm not saying it's impossible, but it's highly implausible.Take a UV light and shine it on the roll of thermal paper. Nothing should stand out, it should fluoresce white uniformly.