That's correct. So it's not very invasive physically, but the fact of being subject to it—of having to comply when there is no suspicion that one has broken the law—is invasive in and of itself. It's easy to imagine more invasive things, but the procedure in question is invasive in nature.
If you can give me two seconds, I'd like to answer your question about possible improvements. Several countries, particularly in Europe, have adopted measures requiring people to provide breath samples even in the absence of suspicion. However, these European programs are subject to a range of conditions, which vary by country. I haven't done a study of the systems in question, but I know that the conditions precedent to the application of the concept differ by country. That's why I strongly encourage you to hear from people about this question, or to study it to see what a reasonable approach would be.