In answer to your question, I'd have to say maybe. Maybe they see us but they're not looking for us.
1. Everyone is in a hurry to get somewhere these days.
2. Drivers of passenger vehicles are typically looking for other "passenger" vehicles.
3. The typical driver doesn't obey traffic signs, particularly speed and stop signs.
4. The typical driver gives only a quick glance prior to entering a roadway, turning onto another or changing lanes.
5. The typical driver these days is inundated with distractions within their own vehicles (radio, cell calls, texting, talking GPS ... ).
6. The typical roadside is cluttered with traffic signal/telephone poles and signs (these are most dense at intersections).
These are probably the most common factors that result in motor vehicle collisions, I'm sure you can think of a couple more. When you take just one or combine any of them you're going to have a collision, its just a matter of when. Unfortunately, the small profile of a motorcycle makes it the most likely target for the when.
For the hot heads out there, there's not a score to settle. Chances are they didn't see you or didn't realized that they saw you. If they did see you and realize it, it was probably at the very moment that they crapped themselves. No one is out to get you! People are people and react in different ways, those who act aggressively after nearly missing you are more than likely mad because you scared the living bejesus out of them.
If you want change then take ownership of it!